You will need to give more information about what you are doing. It might even be a hardware problem...however
I can make a new palette in several ways. This from an existing image.
Attachment:
01-pallete.jpg [ 135.33 KiB | Viewed 4355 times ]
That gets a new palette, saved in the Gimp profile: C:\Users\"yourname"\AppData\Roaming\GIMP\2.10\palettes. Click on that opens the palette editor dock.
That is editable but can be used to set the Foreground (FG) colour for painting with a
single click. Can be edited but that required a double click. Maybe that is the problem.
Attachment:
02-palette.jpg [ 149.99 KiB | Viewed 4355 times ]
Other possibilities: Using the Color History. This gets the colours from the FG/BG color picker, so it will change. If you need to reset it delete the
colorrc file in the Gimp profile.
Attachment:
03-palette.jpg [ 141.87 KiB | Viewed 4355 times ]
Non-editable palette: The stock palettes that come with Gimp are in C:\Program Files\GIMP 2\share\gimp\2.0\palettes. This is read only. Move your custom palettes there.
Check the location in Edit -> Preferences -> Folders -> Palettes.
![Image](https://i.imgur.com/UHMKjam.jpg)
or it might be something else
![Wink ;)](./images/smilies/icon_wink.gif)