Step 1: Visit this link https://dt.amucontrollerexams.com/oaps/user
Step 2: Login here using the username and password created during the filling up of the form. If you forgot your password, reset your password using the options provided.
Step 3: Once successfully logged in you will be presented with a dashboard where all the application forms filled will appear, there will be an option to update preferences/test center choices like the once given below
Step 4: Update your test center preference by clicking on the link as highlighted above.