To change your storage plans, select ‘Storage plans’ on the sidebar from Your account. You can also access this screen from the ‘UPGRADE/DOWNGRADE’ buttons on your Account dashboard, and from the ‘UPGRADE’ button on the Usage overview section of the Welcome screen.

You can change both Project storage and People gallery storage plans at the same time, or only one of them. Just select your new storage plan or plans, and click the ‘CHANGE PLANS’ button. A confirmation window will open with the overview of the changes, click ‘✔CHANGE’ to confirm the change of storage plans.