If your Pen-grip mouse is paired with multiple devices nearby and did
not connect to the one you wanted automatically. You can cycle to the
next device by holding down its second mouse button as you move the
switch on your mouse from "OFF" to "ON".

For mice with only two buttons (e.g. TRACPOINT), hold the rear button.
The LED will flash orange briefly while the ProPoint searches for another device, then light up green for 3 seconds when it connects.

The Pen-grip range can store pairings with up to three Bluetooth devices, and one USB Receiver. So when you pair to a fourth Bluetooth device the Bluetooth pairing which had been used least-recently will be lost. Similarly pairing to a new USB receiver will remove the old USB receiver pairing.