How do you change the region setting on an HP Officejet 7210 from US to European region?

The region setting on HP printers is not user configurable. In some cases, HP technical support can walk you through the process over the phone. It requires entering several lines of code that are specific to your printer model and serial number. You cannot normally use ink purchased from a region other than where you purchased the printer from. If you cannot change the region setting with the help of HP, you can purchase ink from the area that you obtained the printer, it will work in your printer. Refilling your working cartridges is a short-term solution as well.