Sort by column query

I am sure this is something blindingly obvious, so apologies if I have missed something simple.
I am trying to set Opus up so that all folders & subfolders in my pix directory are sorted by "date taken"
So I go into the folder options dialog, insert column for date taken & then put a tick against it to show that is what I want it sorted by.
It does work, but always with the latest date at the top, I want it sorted by oldest date first. There is an option for reverse sort but this is greyed out. Presumably this is what I need but why is it greyed out?
I have tried editing folder formats> manage folder formats, also tried just clicking on column header to sort how I want then clicking save in folder options but still in the wrong order.
Can anyone help with this?

many thanks

The Reverse Order checkbox on the Columns tab is only for grouping, which is why it's disabled (unless grouping is in use):


The one you want is Reverse Sort Order on the Display tab under Sorting Options:


We could probably improve things here, maybe by making it so you can click the sort column to toggle the direction from the Columns tab. (In fact, you can already do this when sorting by multiple columns at once, but not for single-column sort at the moment.)

One thing to note is that you can set up the columns and sorting in the file display, then open Folder Options and everything will already be set up the way you want, including the sort direction. That's often easier, as you can visually see how things are sorted before saving the settings.

That seems to do the trick, many thanks