Autofilling Drop Down in Cell to match cells above WHEN cell below is filled?

Okay, I am trying to build out a time log sheet with drop downs to select from to indicate task performed in that time block.

If someone selects a specific choice from a drop down for the 8AM slot (time is indicated via rows going down as in Outlook calendar), but doesn't begin a new task until 10AM, once they fill 10AM's cell I would like the cells in that column above to auto-fill themselves with the info/task from the 8AM cell data.

I need this to be flexible though, so for example, some people may not fill out another task until noon or 11 or 8:30, etc.

Where should I start on this? Need help with what function or how to build - apologies if this is stupid I am an artist not an Excel pro. -_-