The advice that we would give to our customers, is that your employment start date is the date you became an employee, no matter if that was the same day you became a director, or ten years prior to the day you became a director. The appointment date is the date that employee became a director. If the employee start date is after the director start date; then i'll stick to my original advice - which is your QBO Should reflect real life, and that's what you put. However:
I am going to strongly advise you to send an email to your accountant, or to reach out to HMRC; as i feel this is a matter best answered by someone in a position of Authority. It's something that is an issue of business compliance, because you don't want HMRC to get the wrong information.
I understand that you can be classed as having Directorship without having being classed as an employee. My hesitance to agree that the employment start date is after the director appointment date is because i've been doing this for over a year now, and working solely on Payroll & VAT for the last 9 months, and as far as i can remember, i've only ever seen accounts (10 + per day) where the employment start date was either before, or on the same day as the date they became appointed as director.
@EmilyMockett - Perhaps you can lend us your accountancy knowledge here? What should this customer do? Is there an answer you can help us come too?
Don't worry about editing the appointment date, it doesn't submit - Imagine the number of fines if it did! - You really have to specify the system to submit to HMRC< which is the last step of running payroll.