Could not find the setting in the config screen.

At the top right of the Thunderbird window, click the menu button ≡ > Settings. Type 'setting' (without the quotes) in the search field.

Have enabled and disabled.

What did you enable/disable if you didn't find the setting in the first place?

My apologies for not being clear. I used the enable/disable at Settings-Compostion, unckecking, "Enable spell check as you type." When that did not work, after several attempts of checking, unchecking, rebooting, I went to the Config. I did the empty cache, and reboot, and it did not work. Then I looked for the command for enable, disable, but could not find it. Not being computer literate, I stopped there, and wrote you. Thanks, for your help. John

Have you got a dictionary installed? Go to Settings > Add-ons and Themes (lower left) then Dictionaries. This will list any that are installed. If there aren't any, or none in the language you wish to use, enter something like "English Dictionary" in the Find more add-ons box at the top of the screen.

It is not installed, but I marked English to be used under the Check Spelling uption. Do I need another one?

Yes. If you were multi-lingual you could install several dictionaries and then choose the one to use at a particular time with the thing you have already set.

What happens when you uncheck both spellcheck boxes in settings?

I did, no help. I also tried a different dictionary, Spanish, just to see if it would change what happened. It's still did spell correct as I typed in English.

I did, no help. I also tried a different dictionary, Spanish, just to see if it would change what happened. It's still did spell correct as I typed in English.

Have you given up on being able to help me?

It was a Windows 11 setting. Turned off suggest works, and autocorrect.