My DVD+R DL won't play in my player but DVD-Rs will

I have read several articles and posts talking about changing the book type on the disks to DVD-ROM so that my player will play them even if they are a format it will not play like(+), which my Toshiba SD-V592 does not support. I have been recording onto FUJIFILM DVD-R and they play well but Verbatim DVD+ R DLs will not. I have an external Iomega Super DVD Quicktouch Burner 16x with Windows XP and it recorded fine because the disk will play on my PC with no problems. Does book type changing apply to my equipment. I ask this because I have only heard about this with the NERO and Lite -ON, or something like that. What can I do to play my DVD+R DLs on my player? I would appreciate any help with this.