not the way it used to be

used to be you inserted a smiley and the cursor automatically was behind it not in front of it

yup, you can get behind the smiley by using the arrows but try using your mouse! you can not click any spot behind the smiley.
That ^^^ all works as it should on my Mac (running Safari) and Windows (running Chrome) machines.
I just looked on the Xenforo forum and this is a known problem with Firefox only (Mac or Win). One that's been around for a while. For some running Firefox the issue is intermittent while others experience it all the time. Yes, I know, the problem didn't exist with our older release.
Chrome, Edge, Safari and other browsers are unaffected.
There is a very lengthy
thread about this on the XF forum. Developers and XF administrators on the XF forum say it's an issue with Firefox and not the XF sw. One specific web browser experiences this issue which has nearly everyone there saying it's an issue with the Firefox code vs XF.
ECF search says you are running Firefox on your Win machine? Not the ideal... but maybe try one of the other free web browsers. Chrome, Edge, Opera, Brave, Vivaldi, DuckDuckGo, Chromium or Epic.