Is there a setting to change settings for "This Computer" and not change global settings for other email viewers?
Multiple people read emails from an account. I would like the email to appear new (bold) on my computer. bold text
Alla svar (1)
Firefox doesn't do email, it's strictly a web browser.
If you are using Firefox to access your mail, you are using "web-mail". You need to seek support from your service provider or a forum for that service, and ask about settings such as that. Might be possible if settings such as that are saved in cookies; but not if that settings is saved in the web-mail software per account.
If your problem is with Thunderbird, let us know and we can move this thread to the Thunderbird support queue.