Retail - Rental Express - Error Saving Printer Options

Most likely this is a permissions issue which most commonly happens on a 64bit maching with Windows 7 or newer operating system

As administrator on that PC 

run regedit

go to HKEY_LOCAL_MACHINE/SOFTWARE/WOW6432Node/AXS   

right click and go to permissions

click on the users(that will be running app) and give them full control

click advanced and check the Replace all child object permissions etc... and press ok

Then press ok on the permission screen

That will allow the users to save the printer setup.