You need a DP alt mode adapter for DVI an ordinary one will not work.
When you say USB do you mean thunderbolt? Then you need a proper cable not a USB one or a thunderbolt data/power cable. You will have to google for the right one as there’s lots of cable standards.
Also check if the air can even do more than one extra screen.
Hi,
I am a bit lost.
I got on the USB side: ELECABLE USB to VGA Adapter Cable Compatible with Mac OS Windows XP/Vista/10/8/7
on the thunderbolt got Mini Display Port Thunderbolt to VGA Adapter.
Apologies I thought it was DVI not VGA which is an analogue signal.
With apple not every DVI adapter will work it needs to be different type.
Either way your laptop can only support one extra monitor.
You need a DP alt mode adapter for DVI an ordinary one will not work.
When you say USB do you mean thunderbolt? Then you need a proper cable not a USB one or a thunderbolt data/power cable. You will have to google for the right one as there’s lots of cable standards.
Also check if the air can even do more than one extra screen.