My issue is similar to the one mentioned here: Disable spell checking in Internet Explorer 10 (Windows 8)
I am using Windows 8.1 Pro 64-bit
What I've tried already:
Deactivating the spelling options:
From the following, borrowed screenshot from the old Windows 8 (my interface is German, therefore I couldn't create one myself), I have turned both options off and restarted IE. It's still "correcting" my texts.
Searching for 'spelling correction' addons:
The indicated option in the following borrowed screensnot does not exist on my PC.
Is there any way of disabling it? I prefer a canonical solution if one is available. If not, I am also interested in registry hacks or other solutions.