trying to load 21.2 cin , but computer will not boot the usb, is there anther way?

Have 19.2 mint now, the only disc in the system. used rufus to load bootable iso on a usb stick. no issues.

I tried to boot this changing the bios to 1st boot device being the usb. looks like it trys, but then boots to hard drive. this is a linux system only no windows. I pretty sure I loaded mint from usb iso file booted from this computer, but that was 5 years ago

in the bios I do not see uefi, i do se legacy set to auto. but no other options. tried different usb stick and port no luck. so can I load by a different method? Looked up on internet did not see a clear way to do that