Welcome to Android Central! Which phone do you have? You're saying the memos didn't get backed up -- does that mean the original memos were deleted at some point? Or did you get a new phone and hope the memos from the old phone would restore to the new phone?
I usually advise people against using the stock note-taking apps that a manufacturer puts on phones, be it LG's QuickMemo, Samsung's S Memo, or any other one. The problem with these apps is that the notes you create are only compatible with that specific app -- so if you had a lot of important memos on an LG phone, you wouldn't be able to transfer them easily to a Samsung phone. In addition, many of these kinds of apps don't have a reliable sync or backup method. I think one of the best options is Google Keep, because those notes sync immediately to your Google account, and are accessible anywhere you log in with Google, regardless of the device.