Your preferences should all be the same, except for the styles. The ones for version 2 don't work with version 3.
The AcidTech ones are brand new, just made to look like the older versions.
So if you don't want the boring prosilver style, you'll need to go into your control panel and choose another.
This version of phpBB has many more features, both for the user and the admin. I hope you enjoy it.
