Welcome to the forum, offside99.
Here is a quote from a news item I recently posted on the mainpage. I think it answers your question:
For those of you who don't know, changing the bitsetting means that you change your DVD+R(W) media from being identified as +R(W) disc to being identified as a DVD-ROM disc. This is useful because some DVD players will not read DVD+R(W) discs. By turning these discs into DVD-ROM discs instead it will enhance playability! More information on this can be found in this PDF-document.