Cannot change or see resolution on external monitor

[Giuditta]

Hello,

I am trying to use a HP Probook 640 G4 laptop with an external monitor.  Before connecting the laptop to the monitor, I can see the screen resolution of the laptop screen is 1920 x 1080.  When I connect the two (using a VGA cable) and select the option Duplicate (i.e. see the same on both screens), the resolution is 1920 x 1080 on both screens, which I would expect.  However, when I select to display only on the external monitor the resolution is much lower and I cannot see the resolution in Display settings.  The drop down box where the resolution should be shown is greyed out with no text showing.  The monitor itself is capable of supporting 1920 x 1200 and did so today with two different older non HP laptops (Lenovo running Windows 8.1 whose local screen supports 1920 x 1080 and Toshiba running Windows 7 whose local screen supports 1366 x 788).  I have tried updating the Display driver (Intel(R) UHD Graphics 620) but the problem remains.

Does anyone know how to fix this issue?  The laptop is useless to me if I can't use it with this external monitor...

Thanks in advance

Judith

[robintng]

I have a 32" Philips monitor. Its resolution is WHD 2560×1600. I also cannot change to that resolution!