Wage reporting when hours change weekly after 4 years as an operations analyst

I picked up part-time shifts as an operations analyst and I am confused about how to report them. Any experience at all would help. 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 got easier once I kept a simple log of every call and form.

Keep everything in writing and save the confirmation numbers. It made the follow-up calls so much easier.