How can I set up a bill reminder for every two months

The trick here is noticing that there is a triangle you need to click on when you set up the date.

Add a new bill with the payee, category, account, and amount. Then hit "Next."

On the Schedule Bill Reminder screen, you will see a triangle to the left of the word "Starting."Click on that and you will be able to set it to every two months.

You can also use this for biennial expenses (e.g., my car registration) by clicking on Yearly for the frequency and then choosing every 2 years.

Hope this helps. 

P.S. I just noticed that this is posted under "Budgeting and Planning Tools." I don't use the budget feature so this might not be right. However, it's the way to set up bills under the Bills & Income tab.