POCKETBOOK Android app constantly crashing how to fix

[pw27]

I have Pocketbook e-reader app on my Samsung Galaxy S8+ and it has always worked flawlessly. However about a month ago it started crashing when opening a new book. What i mean is that if i am reading a book, close it out and try to open another book, it just constantly crashes until I force stop and clear cache, which usually will work but then I have to wait for 2-3 minutes for the app to load, I have a relatively large library. I have wiped the partition cache which made no difference. I deleted about 30 very large files, 100+ MBs hoping it would load faster without these. I know that the next step would be to uninstall and reinstall however I have several concerns I need help with. I previously had this issue with another model phone, an Motorola I believe, but when I got this Samsung the app has been perfect until lately.
1) I have about 30 collections which have taken a long time to build and am concerned that if I uninstall and reinstall I will lose my collections. Is that true and is there anyway I can keep my collections if I go through with this?
2) I was considering putting the app on my SD card where my books are but have the same concern, that I will lose.my collections.
I'm trying to weigh if the at least 10 hours it would take to rebuild my collections would be worth having a reading app that doesn't crash all the time which takes away valuable reading time just trying to open a book.
3) One of my favorite fearures, other than the collections, of Pocketbook is that I can make highlights and notes and export them and make a PDF out of all the important parts of the book. If I can't fix the crashing, is there a comparable app with these two essential features I can try? Lastly, does anyone have any other suggestions I can try to fix this?

I can't find a way to contact the developers of Pocketbook so this has been very frustrating. I would be grateful for any feedback at all I read A LOT and this is really taking away from the pleasure of reading. Thank you all in advance I really appreciate it!

[AnotherCat]

I use Pocketbook app but haven't had any problems myself, so the following comments are just as a user (most use is on a Samsung tablet).

1. If you uninstall my experience is that you lose everything unless backed up.

2. I have not lost anything moving this app and its data (or any other app) to the SD card. Backup if unsure.

Pocketbook developer's contact is info@obreey-products.com.

As your are probably aware, Pocketbook creates its own backups (and I think the default is for it to automatically back up?). If you want to be doubly sure then I use MyPhoneExplorer which is free in the store (if you decide to use it; under menu item Extras select Create Backup, follow instructions and it will eventually present check boxes so you can select the application(s) and other files you specifically want to back up i.e. it doesn't force you to back up all the applications, just what you want). Like all backups, nothing is guaranteed but this app has been around for a long time and is well regarded; however, I have not yet ever needed to restore anything from its backups. It does a lot of other useful things too.

John

[pw27]

Thanks for your help John! I really appreciate it. I will try your suggestions and see what happens!