@ fmanolas, Thank you for visiting the HP Forums! A great place where you can find solutions for your issues, with help from the community! I understand you would like to know how to change the printer resolution to 1200dpi on your printer.

Download the latest drivers for your HP LaserJet P1505n to keep your Computer up-to-date.

Don't worry I'll try to help you out. Did you make any changes to your printer? Have you tried printing from a different application? Does the issue persist? Please try few steps recommended below. To enjoy the full benefits you have to install the full feature printer software on your PC.

Ati Radeon 200m Driver Windows 10 on this page. Since you are using windows10 with basic drivers installed on your PC. The maximum resolution is 600DPI. Lexmark X4690 Windows 10 Driver there. HP does not have full feature printer drivers for windows 10. However, you can try the steps recommended below and check if it helps.

In search type devices and printer open devices and printer right click on your printer select printer Properties On the Paper/Quality tab or the Finishing tab select the print-quality setting you want to use. Select FastRes 1200: This setting provides 1200 dpi effective output quality. If you don't have the option you have to use a Windows 7 PC and install the full feature printer software and check if it helps. Asus P8z77 V Drivers Windows 10. Refer the printer user for more information. Note: Refer page 28 for more information.