- You have a laptop with a 13" screen and 1920x1080 resolution and a 4K external monitor.
- You run the laptop at 1x scale.
- You run the 4K screen at 2x scale (pixel doubled).
- You’re running elementary OS 5.x (Hera) or elementary OS 6 (Odin)
Which means that text scale should be 1x when the 4K monitor is plugged in but it should be larger than that (at least ~1.5x) to be legible on the laptop’s screen. (Yes, the manufacturer of the laptop chose the wrong resolution for the screen. It should have been QHD (2560 × 1440) or at most QHD+ (3200×1800) so that you could run it confortably pixel doubled.)
Anyway, it’s not and you’ve already bought it (and it’s otherwise an excellent laptop) but you don’t want to change the text scale every time you plug it into and unplug it from your external monitor.