Rt_ind, welcome to the forum.
Since I don't know which OS you are running, I have provided a guide for both Win 7 and Win 8:
http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01867124&cc=us&dlc=en&lc=en
http://h10025.www1.hp.com/ewfrf/wc/document?docname=c03481733&cc=us&dlc=en&lc=en
In the future, you should always include the make/model of the computer and/or monitor. This information is necessary for us to review the specifications of them.
Please click "KUDOS" if I have helped you and click "Accept as Solution" if your problem is solved.