MBA incorrectly determining external display

I just bought a MBA 2015 a few days ago. I'm still figuring out how to work it, I've used iOS for a while but always used Windows. I had a MBA 11" briefly a couple months ago, and it correctly displayed my monitor (via Thunderbolt to VGA adapter), and I could use the max supported resolutions, 1900x1200 and 1080. That was a 2014 MBA 11.6, and the MBA I just picked up is a 2015 13" and it thinks my monitor is a generic 13.9" when my first one detected it as a 24" correctly. I would think if anything the newer model Macbook would support it better. On Windows it would probably be a driver issue but I have no idea on one of these. Can anyone lend a hand? Thanks

 

Got lucky. The adapter I use is Thunderbolt to VGA and HDMI. I had an HDMI to DVI cable laying around (my dinosaur monitor I use is preHDMI (DVI and VGA only), so I connected it and it detected it down to model number even, and its the better part of a 10 year old monitor. Thanks for the help though!


BTW your way did work for me, the only thing that was wonky is that the highest supported display was 1900x1080 and this is a 1900x1200 monitor so it rendered a bit strange. Did work though so good advice.

Thanks again