As can be seen from the above image, the Norwegian language option is not choosable. I cannot select, nor rearrange the options so that anything but the black text option is at the top. I have read through this thread, and tried reinstalling the language packs without any change.
This is a fresh 18.04 install, where I chose English as the language on install, but it still seems to have installed Norwegian language support based on where my IP was located.
edit: I was later on able to move Norwegian to the top and make it the default system language as well, but it didn't affect the input language which was still English keyboard layout. Turns out this isn't set from the Language settings, but from the Region and Language panel ...
To fix this I did this: