Newbie Seeking Help / Advise

I am using Nero (fairly new). I have been able to create and backup DVD’s, but have recently encountered a problem with media type. Sometimes, Nero will allow me to create DVD’s using DVD -R but more frequently, it requests DVD +R. Is there anyway I can set Nero to allow me to burn to DVD -R?

Thanx in advance for your help / advice.

That depends not on the format but the real mediacode the disc has, if it is supported by the burner or not.