Your Subscription page contains various options for managing your account, including the ability to select a different plan and/or billing cycle.
You can update your billing details by logging into your account and carrying out the following actions:
Click on your avatar located on the upper right-hand side of the page
Select Subscription
Select the plan you wish to enroll in and/or adjust your billing cycle (monthly or annual), your options should look like the image below.
Note: If you upgrade during an existing billing cycle, you will be charged a pro-rated difference for the remaining time left.
If you downgrade during an existing billing cycle you will receive a pro-rated credit towards your Treehouse account for the remaining time left.