If you want to test out a product that you’ve created, or if a user is having problems and you want to see what they see, you can use the “switch to” feature.  Click on Members/List Accounts:

Hover over the email area of the user you want to switch to and you will see the Switch To.  Click on that:

In the upper right hand corner you will see the user you are now logged in as.  You can look at their payments, make a payment, etc.

Switch back to your admin id when you are done: