At the top right corner of the page, click on the “MY ACCOUNT” button.
Here is the direct link! https://library.theprehabguys.com/membership-account/
On this page, click on the red “EDIT PROFILE” button under the My Account section. From here, you can edit your email address and display name. Note: Your username can not be changed. However, your display name can be edited which is what is seen publicly.