When I'm finished working on a PSD file I often convert it to JPG for sending to the printer. I noticed on the last couple of Photoshop releases the PPI is set at 72 in the Image Size menu when I use the Export/JPEG function. I've tried the Save As function but JPG is not one of the save options, only JPEG2000. I want to change this to at least 300, but would prefer to if I could put any amount I choose. How is this accomplished?
It's under Save A Copy. That's where you find jpeg, and all other formats that don't support every property of the original file. This is new from 22.3, but there is a preference setting to revert to the old Save menu.
Export is for web/screen/mobile devices, where ppi is irrelevant. So the ppi metadata are stripped from the file altogether. A file out of Export has no ppi, not 72, not 300. The 72 number appears when the file is reopened into Photoshop, and a default value of 72 is assigned. Other apps might assign other defaults, like 96 in all native Windows apps.