I didn't see your last posts so I got the correct resistors a couple of days ago, replaced the 100 ohm ones and it's now fine so thanks again for your help. I'd love to know why increasing the resistance increases the volume and taking them out altogether has the same effect but I doubt I'd understand anyway.
It doesn't - it's LOWERING it that decreases the volume. 100K is high enough not to have any effect, but the lower you go the more it decreases the volume.