Getting rid of spell check

Scrivener 3 for Windows DO have those options.

You said you tried them, but options are not visible… how did you try those options if you can’t find them?

I’m confused.

In any case, you could add each of your obscure words to the ignore list, or add them to your dictionary. It’s WAY safer this way, than completly shut down spell corrections. In the end, your manuscript must be readable to humans, right?