Sorry to hear you're having issues. To preserve your privacy, DubScript doesn't ask for nor collect your contact info (which is how it should be!), so instead i'll try to respond here and maybe anyone else having this issue in the future can benefit as well.
You didn't quite say what in particular is happening when you experience the app closing (is it a crash?). Is there some action you do that initiates the close every time it happens? This would be helpful to know in debugging the issue.
Backing Up (a bunch of ways)
First thing to do in a situation like this it to make sure you've backed up all your screenplays off the device as this might be a sign that the device itself is failing, especially if as you report the crashes (if that's what they are) is inconsistent and have been increasing over time.
There are a number of ways you can do an offline backup (see the Help & Info menu item, then read the "About DubScript" section), but quickly--
You can email your screenplay files off the device -- in several ways. You can open the script, and sometime before you experience the crash, choose the "Share" item, and select an email program. This should add the screenplay to the selected email app as an attachment, which you can then mail to yourself. You can also do this by copy/pasting the text and pasting it into an email.
Another way to back up off-device is to hold down the "Save" icon (the one that looks like an old style "floppy" disk- the thing that turns red when you edit the script). And save the file "Fountain" to a new location- including via Cloud Apps-- by selecting the target location when you save it. So, for example, if you have Google Drive installed, you can select Drive as the location.
Similarly you can go to the menu item under "Recovery Backups" and find a saved backup, choose it, and select "Recover from Local Backup". This will also allow you to save, and once again if you have a Cloud App installed and configured right, you can save off-device this way.
Yet ANOTHER way to save the script off-device is to simply Copy the text from the editor and then open up Google Docs (if you use that) and paste into an empty document, which should save the text to the cloud.
Here's another way to back up: If you have the official Android Files app from Google installed, use it find your saved screenplay files and then choose the three dots to bring up the menu for that file. "Back Up to Google Drive" should be an option (at least in the lastest version)
If you don't have that app, you can get it from the play store at https://play.google.com/store/apps/details?id=com.google.android.apps.nbu.files
There are many other ways to back up the files (via the Google Drive app directly, using an external SDCard if you have that, etc.) but I think you get the point. Make backups before you do anything else.
Check your text for anything weird
DubScript shouldn't crash from strange UTF-8 characters, but just in case, check to make sure that the screenplay file you're loading is 100% text only and doesn't have any unusual characters embedded into it that might somehow be tripping up Android's native editor.
In fact, if you have an old version of Android, make sure that it's up-to-date with any updates. For example, Android regularly updates itself to support new emojis, so if for no other reason you should keep everything up to date. If you go to the Android Settings, usually under System there will be an option to check for updates. (Make sure you've backed important things up first).
Without having any info besides "the program closes" regularly, it's hard to know exactly what's to blame. Is something specific reliably happening before or during the problem?
Let's say the text is to blame-- you can try scrolling through the project to see if you can narrow if there's a particular area that makes the program close. Does the crash happen when you scroll through or edit a specific section? Is there something unusual there that looks suspicious? If so, you may have just found the bug!
Another more obvious question is this-- does the program have issues with ALL documents or only one or two? Does it crash when it's just sitting there or do you have to be doing something to trigger the problem?
One way to experiment to see if the cause is in the text itself-- you can try deleting the top half of the file you're editing. If it's suddenly stable, then something in that top half might be the problem! You can put HALF of what you took out back in. If it's suddenly crashing, you know that the half you put back was the problem. If not, you can put the OTHER half back in.
You can repeat this process (called "bisecting" as you keep cutting the problem area in half) to target whatever is causing the crash.
If you noticed the problem suddenly occurring after a certain day, and then app itself wasn't changed, then something in the file may have become corrupted. So another way to locate what in the file is causing the problem is to revert to an older version when the problem *wasn't* occurring. Use the "Recovery backups" menu item to try recovering an older version. If this file doesn't crash, something new must have caused it. Maybe this will help find it?
If you can isolate that some specific character leads to the crash, say every time you move the cursor over it or something, knowing the problem will go a long way in finding a solution for it.
Try updating DubScript to the beta
DubScript is always being updated, and the newest version is usually in the beta aka "testing" releases, which you can opt into trying via the Play Store.
See if this issue was addressed there-- sometimes simply updating an internal "library" file provided by Google can fix intermittent or unusual crashes due to internal Android conflicts.
The beta can be signed up for here:
Try resetting DubScript
Once you've got your backup -- AND VERIFY THAT EVERYTHING IS BACKED UP OFF-DEVICE FIRST, you might now try to clear DubScript's settings as a last resort to see if the problem goes away. Perhaps something strange got corrupted in the settings (?). In any case, clearing out the program is something you may want to try.
There are two types of app data to try clearing out--
The cache -- this is a less destructive type of data to wipe. You can usually remove this stuff safely and any files you've deleted will be recreated the next time you run the app.
All app data -- this will return your app to a "fresh" state. It will wipe all the settings, cache files, state, which script gets loaded when you start editing, and more (including the on-device recovery backups!).
Clearing the app data shouldn't delete the screenplay files themselves (except for the above-mentioned on-device backups), because they are saved as individual files in your device's main storage system or in the cloud- wherever you selected to save them. Regardless, just to be safe, I want to emphasize to first have reliable backups (and backups of backups can't hurt either). Think of deleting the app data as the equivalent of re-installing the app fresh.
If you do want to give this a shot, you can clear the app data via Android's system settings. Depending on your version of Android, this can look slightly different, but it's usually something like Settings -> Apps -> DubScript -> Storage & Cache and then "Clear cache" & "Clear Storage".
Again, and sorry to drive this point into the ground, but only do this once you are sure you have everything backed up off your device.
If you have further questions, post here with a more detailed explanation of the problem and what seems to trigger it, and I'll try to respond. It would be helpful to know what version of Android you're using as well as the version of DubScript.
As this is a public forum, don't post anything proprietary or private or anything.
Hopefully in future, anyone else having issues can find this convo and gain some help as well.