Word Online Won't Stop Checking My Grammar and Spelling

When I write I don't enjoy Word online making my story light up like a pinball machine. Double blue lines, light red highlighting, red squiggles, popup boxes asking if I'd like to see suggestions etc. It's all distracting and disruptive. So I've been trying to disable all that. Later I might be interested, but not now.

I go to Editor > Set Proofing Language > in the language box I click "Don't check spelling or grammar", then OK to close the dialog. All the red squiggles and shading and popups are all still showing in the document. I go back to the language box and that key checkbox is unchecked, as if "OK" didn't save my settings. I close and reopen the document; maybe that will save the setting, but no joy then either. What am i not doing correctly? Is there something in the browser I need to do? Or use a particular browser?

I'd rather be writing my story,

Mark