I now will try to investigate this a little deeper via the database to see what I can find out.

I recently transfered a phpbb forum to wpforo and there are several instances where the posting date is not showing in "m /d / yyyy" format but is showing in "d / m / yyyy" format.

I'm stumped with trying to figure out what I can do to fix this.

Hi @michael-tcr. You can try this:

#1) Go to your Forum Dashboard >
Settings
Features tab
Enable WordPress Date/Time Format
Set to YES
Click Update Options.

#2) Then on your Wordpress Dashboard >
WordPress Settings
General
Select the Date format style you want (m/d/Y) 
Click "Save Changes"

#3) Then go back to your Forum Dashboard
Under Forum Maintenance
Click the following:
Rebuild Threads
Update Topics Statistic
Update User Statistic
Delete All Caches

#4) Press Control F5 twice on your frontend and test it again.

Also it helps to test it on an Incognito Window or in another browser, especially if you are also testing on a Mobile Device (since Mobile devices have hard caches).

#5) Also, might help to check your "Server Information" (same area as #3), and compare it with the wpForo Server Requirements here:

https://wpforo.com/docs/root/wpforo-installation/server-requirements/

(I had a date issue when I started my first forum as well, that's why I know that if one is in a lower than 5.6 php version, it seems to cause some issues with how the dates display  - it is not a wpForo problem, but a php version issue which can be resolved when we call our Webhosting company and ask them to upgrade to a higher version of PHP -webhosts can fix this in 30 minutes to 1 hour, well, mine did.  :-) ). 

If the above suggestions don't work, maybe if you leave your URL, the Support Team and the Community can also try to help. Good luck and God bless you.  :-)

I'm stumped with trying to figure out what I can do to fix this.