Best answer as chosen by user JimM99: There are two ways to easily change to different accounts
Your two choices:
1) Preferences/Store/Apple ID click on your ID (Apple ID: firstname.lastname@example.org)
You'll get a pop-up that gives you the option to sign out. Do that and sign in with the other account.
2) Or - App Store/Featured scroll all the way to bottom of page and click on your Apple ID there.
Same procedure as above: sign out and then in to the other account.
Hope that helps.