i keep getting notices telling me that my C drive is running out of space.i have therefore tried to put itunes onto my external hard drive(loads of space!)but when asked which drive i would like to use,i am unsure of how to change the default setting from C to the external drive.

Welcome, barnsley.

I think this post needs to be moved to a more appropriate place. Before I move it, I need to make sure - are you asking how to change the defaults in iTunes? That would not be a hardware problem and I don't use iTunes. Still, the typical method is to choose the drive letter to the external drive, as shown under My Computer.

sorry,i probably didn't explain it properly.when trying to download itunes,because drive C is identified as showing little space,i am asked which location i would like to use.Drive G (external hard drive)is listed but i am unable to change the setting to use it.i was just wondering if there was any way i could change the default setting

Okay, so you are asking a question about iTunes. I am moving this post to Entertainment, hopefully someone there can help you.