Notes on Mobile
Category notes are available on all devices. Tap on a category then Details to show the Notes section. Press return on the keypad for a line break when writing or editing category notes.
Account notes are available for iOS devices but aren't currently available on Android. On iOS tap the account name, tap the More button (three dots), Edit Account, and enter in a note!
If you want to add a month note, you can do that from the web app!
We're constantly working on new features to improve YNAB. The Feature Request Form allows you to share your thoughts and suggestions directly with the Design Team.