How do I locate my “app data” on my external hard drive …. Specifically the browser app data.
how app data was moved to external hard drive, copy/paste?
Can you be a bit more specific about your question? Normally the %appdata% folder is stored on the local hard drive. Is this a backup disc, an internal drive that's been taken out and used as an external drive or perhaps you mean a different "App Data" than I'm thinking of?
Half-guessing, I can offer this information. The ordinary AppData folder is hidden, so you need to go into Organise=>Folder and Search Options, click the /View tab and tick "Show hidden files, folders and drives" which will cause hidden files and folders to be shown. The folder is located in the user's profile (in other words C:usersappdata so you could look for it in the external hard drive in the analogous location.