Saving cell data based on drop down list

I dont know if this is possiable but there are two things i can not figure out.

1. We a user selects their name from a drop down list i want the hours they entered previously to show up , right now when i select a new name the cells with hours just stay the same.

2. Each person must input hours two weeks at a time, sometimes one week is in one month and the other week in another. But i need to sum totals based on month. How can i check for this so hours are put in the apporiate month in the Dashboard tab. Thanks!

Well i was able to figure out problem 2 but i still have yet to figure out how to do 1.