samthebest :
As per the image:
Intellij adds : String to my code, I don't want Intellij to add random text to my code. Is there any way to disable this completely?
I've found some settings that allow my to uncheck "Foreground" and "Background", but the weird grey box still remains after unchecking these:
Justin Kaeser :
Your screenshot is missing a bit of context, but this looks like it is a "type mismatch" hint. The best way to remove it is to fix the type error ;)
If you would like to disable this way of highlighting type errors, go to Preferences | Languages & Frameworks | Scala | Editor | Type mismatch display and select "Highlight expression"
