If your team's currently on an annual subscription, that would explain what you're running into. Moving from annual to monthly isn't something you can do yourself from Admin settings, unlike switching from monthly to annual, which is self-serve. Since it involves reviewing the specifics of your current subscription, our customer support team needs to handle it directly with you rather than through a menu.
For your account's security, we're not able to get into the specific details of your plan here on the forum, but I can see you’ve already contacted our customer support team (Ticket #2046684). Our team will be following up with you directly to help sort this out.