Changed files are not synchronized

I’m running the NextCloud app version 3.0.1 on Android 7.0, and the NextCloud server 13.0.0 on Arch Linux.

I have a few folders configured under “Auto upload” on the Android app. I see that when a file is added to one of these folders, it is indeed automatically uploaded to my server. However, if an existing file is changed, the file changes are never uploaded, and the server retains the original version.

I’m not sure if this is how it is supposed to work, but I would like it to work differently.

I have a password manager program, PasswdSafe, and I want its encrypted password file to be backed up automatically after any changes. How do I do this?

Thanks for any help.