How can I access my Gmail account (a) from a different computer (b) with a different Gmail account?
When I entered gmail.com in computer b, it immediately switched to its own saved Gmail name and password, which couldn't be modified.
How can I access my Gmail account (a) from a different computer (b) with a different Gmail account?
When I entered gmail.com in computer b, it immediately switched to its own saved Gmail name and password, which couldn't be modified.
You can log out of the existing Gmail account, or you could open up private browsing or a different browser. Chrome has incognito, Firefox has private windows, IE has InPrivate windows. Any of these will not use existing cookies, allowing you to log into your own account without messing with the currently logged-in account.
A number of ways of doing this:
Use a different browser or private browsing, as @Ryan suggests
If you see the wrong Gmail address and can change it, there should be an option Sign in with a different account