As others have noted, you likely have a scald preventing valve.

What make and model is it?

Can you find a diagram of it at the website of the manufacturer?

If not, can you find an 800 number for the manufacturer to call for
help?

If not, can you contact your leasor and ask them for help?

If not, can you remove the handle or nob from the shower control?
The Limit stop may be obvious under there.

good luck
Phil