Remove update prompt from a single login

You’re welcome! FYI, there is an existing feature request that is proposing the functionality you were looking for:

 

However, the “Never Ask” option (which is now available when prompted to add a new password) works by adding sites to the Excluded Domains list, so if the feature requested above is implemented, it would probably still not be synced across browsers.

Here is an additional feature request on the topic of cross-browser synchronization of browser extension settings: