Click on your name on the Top Right Corner to open the User Menu
Select “Account & Settings”
This will open the Account & Settings Window. In this window, click on the Plan tab.
Select a new Plan and click Update Plan below.
Note, when you upgrade, you will be pro-rated by day and invoiced immediately. Your invoice will be equal to the amount of time you used of your old plan for the period and the amount of time left on the new plan still to use. You will only be charged the difference between the two plans.