can you walk us through the steps you are doing and then what occurs after each step?  you are using the forum tools, right?  and no caching plugins on your site for the forum page?

I am using the forum admin 

Forums and Groups >> Edit Forum >> Pick the position (before/ after forum xyz) >> Click “Update Forum”

Even after picking the position, none of the forums move.

We’re running version 5.4.0

This is not an area we are doing too well on at the moment which is a bit of an embarrassment! So – he full story.

The methods used to move forums about had been getting creaky for a while and I think really started to break down before we noticed fully. It is,actually, some of the very oldest code in the plugin and I think things had moved on around it at, shall we say, a quicker pace!

So in version 5.4.1 we finally scrapped it and introduced a Group and Forum ‘ordering’ tool. This is a much easier way of doing it and allows you to drag and drop your Groups and Forums about to get the order you want.

The problem with that however, as we found after it had been released, is that anyone with subforums – well actually probably multiple subforums – were then vulnerable to an ordering corruption. This is not ALL users with subforums but some – depending upon their existing data. As I said above – embarrassing.

In turn this issue has now been corrected and will be a part of the next update to SP.

SO – if you do not use sub-forums then I would suggest upgrading to version 5.4.1 to make use of the new ordering tool. If you DO use subforums I would hold off until 5.4.2.

If neither of those options is possible it is usually possible to get forums to move using the old code but sometimes you need to move others – like moving the ones above tp sit below the one you need to move up. A pain and not ideal but should usually get you there…