Red underline of the spelling checker

[Arjuna A52s]

My phone is A52s and the red underline of the spelling checker for Samsung key board doesn't work. I tried to change default spell checker to Gboard but after few times it going back to Samsung key board. please help me to fix this error.

[AndrewL]

@Arjuna A52s: Please head to Settings > General management > Samsung Keyboard settings > Auto spell check, and toggle on your preferred language(s). Tap the back button > Auto replace, and toggle this option off. With Auto replace enabled, incorrectly spelled words will be underlined in blue, presumably as this feature wants to automatically replace the word with the correct one. If you toggle Auto replace off, the incorrectly spelled words will be underlined in red as expected. I hope this helps. 

[DanSwano62]

Hey dude, did you manage to find a solution for this? Literally the same thing is happening with me, but my phone is a S22. I tried everything i could, but everytime the setting reset back to the samsung spellchecker. It works for a while, but something is reseting the settings and change the gboard spellchecker to the samsung spellchecker. This is driving me crazy, I tried pretty much anything with no sucess.