User Role Editor WordPress plugin allows you to change standard WordPress user roles capabilities with easiness of a few mouse clicks. Just turn on check boxes of capabilities you wish to add to the selected role and click “Update” button to save your changes. That’s done. In case you made some unneccessary change you always have the “Reset” button to return to the default state of WordPress user roles.
Why it could be necessary? Let’s suppose you wish that you multi-authored blog contributors upload their own graphics to use in their posts. WordPress “contributor” role has no such capability by default. In such situation you have needed to change user role capabilities manually using SQL client as I described at How to change wordpress user role capabilities, if you have enough knowledge in that field. But what to do if you have not? Good news – This task is simple now, just use the “User Role Editor” plugin :).