It seems KER GUI sizing (HUD 1 and HUD 2) is only compatitable with the resolution of KSP when you installed it.
When you change resolution, KER may misbehave severely.

I have a 1080p laptop.
Normally I dislike playing fullscreen, so I use 900p for normal playing. It works fine.
However, when I record video, I play in 1080p fullscreen. Then the GUI sizing (judged by the distance of HUD 1 right-border and HUD 2 left-border) is still same as that in 900p. This cause HUD 2 to be overlapping with stock altimeter. Restarting KSP dont get things better, only reinstallation works...
What I observe now is that KER use the left-top corner as zero point and then place HUD 1 and HUD 2 always at the same absolute pixel coordinate relative to that corner.

HUD1 got all corrupt on me, and I never changed any screen resolution, never changed monitors, nothing.

Kerbal Space Program - 1.11.0.3045 (WindowsPlayer x64) en-us
OS: Windows 10 (10.0.0) 64bit
CPU: Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz (12)
RAM: 16282
GPU: NVIDIA GeForce GTX 1660 Ti (5991MB)
SM: 50 (Direct3D 11.0 [level 11.1])