For example the income reminder could be set up to repeat on the third Wednesday of each month.
How to set up reminder for 3rd Wednesday of month (contains both Windows and Mac instructions. Mac users please scroll down a little)
I totally missed this when I was setting it up. It looked like that field only had "day" in it. But I see if you select 1st, 2nd, 3rd, or 4th, it changes to "day" plus mon-sun. Problem solved, thank you!