Hope someone might be able to help.

I've got an iMac that I bought off someone and I seem to be having difficulty with the mail app.

When I try to send a mail direct from the app rather through outlook on the web browser i get an error message saying can't connect to the account "hotmail" and prompts me to enter the password. However, the mail account it's asking me to enter for isn't my own despite the fact I've set it up on system preferences.

I'm assuming, rightly or wrongly, that this email address might be the original owners. Is there any way for me to change this email address somewhere as I'm struggling to find a way

Thanks for looking