Wage reporting when hours change weekly - first time posting

I picked up part-time shifts as a mechanic and I am confused about how to report them. It has been weighing on me all week. The form asks for gross earnings, which I do not see until later. Did anyone get an overpayment notice from a mistake?

Thanks for writing this out. I went through something close to it last year, and it settled down once I kept a simple log of every call and form.