Unable to change modem configuration for a different network provider SIM.

I set up fine and the unit was connected. The Sim was EE. When i got to the location, unfortunately no signal. There was a Vodafone signal and we had a Vodafone Data sim. So replaced the EE sim with the Vodafone SiM. Connected the unit to laptop and logged in. Couldn't see any options to change network provider (as happens when the unit powers up first time. I went through the menu and found full reset. I did this twice - no change.
How fo i change network provider when i put a different SIM into the modem?