Manual Metadata Lock

The way you were doing it is actually working… unless the poster you’ve picked is no longer available (e.g. if it’s been removed at its source or there’s a licensing issue). Personally I prefer storing my posters as local assets alongside my media.

That being said, there’s already an existing suggestion to change/improce the poster locking behavior. If that’s what you have in mind, please comment/vote in that thread in order to help us avoid distracting or cannibalizing votes.

In addition there’s existing suggestions asking for a one-click option to lock all information of an item or an entire library respectively.

Unless I’m missing some unique aspect of your suggestion I’ll close this thread as a duplicate.