Okay, luckily your problem is really easy to solve. Open the report in design view again and click in the gray space at the bottom of the report. (So you aren't in a section, you just get the report properties) Go to Sorting and Groupings.
Go to the Employee Line. At the bottom it says, Group Header and Yes and Group Footer and No. Change Group Footer to Yes. Then go back to the report in design view and move that Averaging Textbox to the Employee Footer.
That should do it for ya!