how to change notifier module "Private Messages" text to say something else?

I've searched the FAQ and forum and do not see an answer to my question: I have the notifier module enabled in a fixed position. What appears on the frontend is "Private Messages" with a mail icon next to the text. I want to change "Private Messages" to just say "Messages", how do I do this? I don't see anywhere to change it in the Uddeim component or the module, and it doesn't show up in the Joomla language manager. Is there a file I can modify through ftp to change the text?

Thank you!

So I disabled the "Private Messages" header, but I still need to modify the "Attachments (max. x.0 MByte per file):" text at the bottom of the compose message page--I want to list the allowed attachment types. Could you tell me which folder/file that is located in? Thank you!

You can modify the language file located in \language.utf8\

Thank you!