PHPBB3 to Invision Problem

Basically i've found a weird problem, I was switching my forum accross from it's old PHPBB3 layout to a new Invision based one, while I was using the colours options to change some of the details of the menu's the entire thing suddenly glitched, started displaying the background of the old PHPBB3 forum and fell into a jumbled unorganised mess.

Restoring it back to the PHPBB3 version allows for the site to remain usable but whenever I try and switch to invision I get the same problem, and i've noticed it's even keeping the old colouration settings from the old PHPBB3 version instead of switching to whatever I set as the invision colour scheme.

Seriously, has anyone got any idea what went wrong?
I can't seem to fix this, even using CSS hasn't helped!

Please take a look at this topic. https://help.forumotion.com/hitskincom-support-f48/my-themes-are-changing-by-themselves-t13102.htm

That helped a little, but it's still pretty weird,
doesn't seem to look right.

What looks weird now?