I hook my Surface Pro 3 (2160 x 1440) to my monitor (1920 x 1080) and swap Photoshop between them. I used to be able to do this with no problem.
Now if I swap Adobe Photoshop to my monitor, the interface is very large. I'd have to restart my computer and make setting changes so it will appear normal on my monitor. However, now moving it to my Surface, it does the exact opposite and becomes extremely small.
This is only a problem with Photoshop, my other Adobe products seem to adjust to the scale fine. Is there a setting I may of changed that might of caused this?
In current versions, the Photoshop UI scaling options are in Edit > Preferences > Interface, I'd start there.
I have tried changing the interface to a smaller scale, but doing so may make it useable on the monitor but very tiny on the Surface. I would also like to reiterate that this was never a problem before and is currently not a problem with other Adobe software.
I am using Windows 10 and Photoshop 19.0