Turn on / off Conversation threads

I have just purchased a Samsung A51 / S51 and use Yahoo Mail. Emails now are placed in conversation threads which makes viewing confused. Apparently you can toggle this option on or off either via Settings directly or via Profile. However this option does not seem to show up in my Settings and accessing my Profile is not so simple and / or seems not to make any difference. It is almost as if someone has gone to great lengths to make this simple operation complicated. Can anyone shed any light?