Dual monitors with different resolutions

I’m running 3.5.1 with 2 Lenovo monitors which are exactly the same. One is connected to the VGA port of a Radeon HD5450 graphics card, and one is connected to the DVI port of the same graphics card using a VGA to DVI adaptor. The problem is that only one monitor is recognised and allowed to run at 1440 x 900 resolutions, while the other monitor is not recognised as as such is only allowed to run at a maximum of 1024 x 768.
Is there any way to force the unrecognised monitor to run at the higher resolution?

(PS… I was using a Nvidia GT210 graphicS card which did the same)

Ignore this please - I’ve solved the problem with a little help from Youtube!