I recently upgraded from Version 9 to Version 10.
All is well save for one small issue. The 'names' column displays short names rather than the long names I'm used to. I have tried to find where to change this amongst the preferences and have searched the forums - it could be staring me in the face - but I can't see where to find the option to do this.
So apologies in advance and appreciate any guidance.
Do you mean names in 8.3 style? 
I should have added an example.
By way of example, I have a file called 'business expense.xls' and in the first column of the lister (under the name column) it is shown as 'BUSINE~1.XLS'. So it is short (8 characters) and has been CAPITALISED. If I click on the file to rename it - it expands out to show the full name but shortens it again to the same format as above (6 characters plus ~1)
If you look in the folder tree view on the left - the sub directories are all in their long name format, but on the right, they are all short (6 characters), capitalised with ~1 at the end of the name (8 characters in total).
Hope this helps a little more.
Hi and many thanks !
The issue has now been resolved and was highlighted in the posts above.
I have a registered copy of V9 and took the chance to use the trial license for V10 to see if it was worth upgrading. It worked fine and now, given the above, can pinpoint when it went wrong. I was asked to update the license certificate - this is when it went awry. Even though I had closed the lister, it was still open in the taskbar. So totally closing Directory Opus and starting it again fixed thing.
I'm sorry to have posted the question but am really pleased you've addressed the solution !