I am using a second monitor. When I plug it in, it use to automatically find the right resolution.

But when I plugged it in today, it was set to mirror. I unchecked mirror displays and set to the right arrangement, however, the resolution on my monitor is incorrect. On my laptop screen, there are no options when I click scaled, only larger text, smaller text, etc. On my monitor screen, there are very few options when I click scaled, none of which are appropriate for my monitor. When I hold the option key and click scaled, there are a few more options, but they are all lower resolution. When I plug the computer into the monitor, I get a pop up from the monitor saying current resolution is 1920x1080, but it recommends 2560x1080. Neither of these resolutions shows up in the options for my laptop's screen or for my monitor's screen. I have no idea what changed and I have not done anything to my laptop over the weekend that would cause a change.