Resolved how to change resolution on 2nd monitor only ?

I have Windows 10 on a laptop with 1366 x 768 resolution, and a 2nd monitor - a 25 inch job . I display the same view on both screens . However on the big monitor it is only shown at 1366 x 768 ( presumably)_ so that a lot of the screen is wasted.
Using Settings/Display I can see both monitors but one is greyed, and I can't get the system to recognise it and hence can't change its resolution.
I know that it can be done - it used to be done, but somehow I have lost it.

 

I have been a multi-monitor junkie almost forever. And for almost as long, I have used UltraMon to manage them. It is not free ($40), but that is a one time, lifetime license fee and it allows you to use it on all your "personal" computers. In my opinion, it is well worth the cost and it will easily let you set different resolutions on each monitor - up to 10 monitors per computer! I have my Windows desktop stretched across my two monitors to make one big desktop, but it will let you mirror the displays too (and again, with different resolutions).

See also DisplayFusion which has a limited free version, or a pro version too. The free version, IMO, did not have the features I needed. And the pro version was more complex with way more features than I needed. There is a $30 license but it is good for one computer only. If you currently, or in the future may need to install it on more than one computer, there is a $44 option (but again, these are for personal - not commercial use).

So for me, spending $40 for the features I needed on all my computers is a better deal than spending $44 for features I don't need. So UltraMon is the one I use and recommend.

 

May sound silly but:
In display settings what happens when you left click on the monitor that's greyed out?
Also - at the bottom of display settings - under Multiple displays do you have Extend these displays selected and NOT Duplicate these displays

 

When I do left click, that monitor becomes hightlighted. No settings changes are made.

And yes, I have "Extend these displays" selected. That's because I want one big Windows desktop so I can, for example, have Word open on one monitor and my browser open on the other.

Since you said you want the same display on both monitors, you would select "Duplicate these displays". This is the typical setting many notebook users use when giving presentations. That way, they can use their notebook monitor while their audience is viewing the larger screen but everyone is seeing the exact same thing.

Now of course, you have to tell your notebook to use both monitors. That takes a Function Key + F-key combination. On my Toshiba, that is Fn + F5 to cycle through notebook screen, external screen, or both.

 

Bill;
Guess wasn’t clear. Was responding to Geoff and his problem..

"Using Settings/Display I can see both monitors but one is greyed, and I can't get the system to recognise it and hence can't change its resolution."

 

No. You were perfectly clear? I just was not paying attention. Sorry.

 

Consider it solved. I took a hint, and googled how to do it with my laptop details added. Got a page which dint actually work, but gave me a lead to set the large monitor as the only one, and I was able to get the resolution right with that. So my laptop screen remains black, but that doesn't;t matter.

Anyway - thanks to all who helped