I've set up a chromebook virtual device to look into the resizing issue.
Regarding the other issue - to open an existing file on your device, please open it outside the app and select 'Open with yWriter'. This will create a copy inside the local app folder that the app can access.
To share it outside the app again, you can Save As... to Dropbox (more cloud options will be added eventually) or when a project is open, click the 3 dots in the top right and select Share... then choose the target location which should include the option to save to files on the chromebook.
If you're curious, the reason this app cannot directly access files outside of the local app folder is due to some security restrictions on Android apps. (There's some developer-facing information about this here
https://developer.android.com/about/versions/11/privacy/storage#other-apps-data). You can open a file outside the app with the 'Open with yWriter' functionality, but due to this limitation I can't allow the app to auto-save back to that file's location automatically.
Hope that makes sense. Let me know if that works for you.
I hope to add some documentation, in-app tutorials, and UI changes (such as to the file selection menu) to make it more clear how to open yWriter files and what the app can and cannot do.
Thanks,
Liz
yWriter App Support