Custom Sound Notification; Don't Want UNIFIED Inbox

App ver. 5.800
Android 11 build RQ3A.210705.001

I regret upgrading to the K-9 Mail because all my custom email sound notifications are GONE.

I never use the UNIFIED inbox.

How do I get the settings back from the last official version of K-9 mail that was in the app store? (Sound notifications and the separate email list?

See K9 Notification sounds and quiet time to read how to change the notification sounds. You can disable the unified inbox on the general settings screen.