I have users input number of hours for a particular month/day, and it updates
a table in another sheet...this works fine, until...the user changes days,
and then the original info gets zeroed, not kept.

For instance, user enters 8 hrs for january 1... which then gets written to
table col/row for january 1. However, when they go to enter hrs for january
2, january 1 info gets set back to zero, and january 2 reflects the 8, etc.

How can I "freeze" the original input once it's entered without subsequent
info updating it?