Some Admins will set all their request queues to a status of Queue or something along those lines or put all their request queues in a certain Portfolio.
If you're not sure what might have been done, you can create a project report with the filter: Queue >> Is Public = Company, Group, Private, Public
This seems to pull all projects where on the Queue Details page, "Publish as Help Request Queue" is checked, which then allows those projects to show in the first dropdown on the Requests page, and the queue topics from those projects to show in subsequent dropdowns.
This will give you easy access to all your request queues going forward.
Thank you, Heather