Try this with your GH3 and tell me if the camera remembers the shutter speed.
1. Mode Dial to Creative Video Mode.
2. Select a desired shutter speed.
3. Custom Set Menu select C1 and save the current settings.
4. Mode Dial to C1 to insure the setting is correct.
5. Mode Dial back to Creative Video Mode.
6. Change the shutter speed.
7. Mode Dial back to C1.

My camera will not remember the saved shutter speed for any Custom settings. Very annoying when you want to switch from a shutter speed of 1/60 for 30 fps and a shutter speed of 1/125 for 60 FPS.

Is the problem me, or the camera?

Mine doe not save the shutter speed or f stop. You can save the ISO and many of the other settings, but not these settings. Thye will remain at what you set them in Creative Movie Mode.

Willard;
The most important settings are shutter speed and f-stop. Panasonic needs to include those in a firmware update. Every Canon camera I have ever used will retain those settings in the Custom Mode settings.

Always something

Kent