Wage reporting when hours change weekly (update)

I picked up part-time shifts as a retail manager and I am confused about how to report them. The form asks for gross earnings, which I do not see until later. Who can I ask without risking my claim?

The claimant handbook has worked examples for part-time pay. Mine was clearer than the phone line.

I estimated and then checked my pay stub. When there was a small difference I wrote to the agency to correct it.