Do you have auto-update?
The windows version features auto-update, and we plan to implement the same for Mac in the future. To update manually, just download the latest version from decentr.net, and either run the installer on Windows, replace the .app on Mac, or install the new .deb on Linux platforms. No data is lost during this manual update process, as the local user data is stored in a different folder. Linux versions won't support auto-update.
When updating Decentr manually, we highly recommend having your seed phrase backed up just in case there are issues with the install. Depending on your system platform and account permissions, Decentr may ask you to sign in again after manually updating, and you will need your seed phrase to access your account. We cannot restore an account that you have forgotten the seed phrase for.