Turn off the mouse under dongle mode. Insert the dongle into a computer, and wait for the computer to recognise the dongle (a pop-up message to say it is detected) Turn on the mouse whilst pressing both the left and right buttons. (Make sure both buttons are pressed down during the switching on the process, try to hold both buttons down for 5 seconds to allow the paring process to complete) The dongle should then be paired with the mouse.