How do you change the beginning of the week to Sunday on a form?

Hello! I perceive this should be fairly simple to fix but it is perplexing to me! When staff are completing our form they frequently set a deadline of Saturday (we are closed on weekends) and I couldn't figure out why until I filled out the form myself and it shows the days of the week starting with Monday and ending with Sunday, so people are selecting the second last day of the week as the deadline, thinking it is Friday. I try to remedy this by editing the form, but it shows the days of the week as Sunday to Saturday when in the editing mode! Help! LOL See screenshots attached. The calendar appears as Sunday to Saturday in the sheet that the form is used for as well.