Once a forum has been set up, it is very easy for a teacher to change the subscription mode, using the options shown in the following screenshot - however there is no warning when someone does this. I have on a couple of occasions got caught out, when I have accidentally caught the wrong link (problems with using a touch screen), Also in some themes, there is a slight lag time as the administration options appear and expands, which for people like me sometimes results in clicking on the wrong thing.

If changing a forum from say Optional to Auto (or Forced) is quite significant (if there are lots of people on the course), which in turn has impact in terms of GDPR (sending emails to people who don't want them).

When someone clicks one of these options, could this in turn take them to a warning screen clarifying the consequence of what they are doing, then getting them to confirm to proceed?