I'm surprised no one has yet answered my above question as I have now managed to find the answer for myself in another thread, here. It seems that the Show Different Channels Separately button was only introduced in version 8.42 of WavePad - and as I stated in my original post I had v6.38.
So I have now upgraded to the latest version (9.63), but although I now have a Separate Channel Editing button, I can't seen any way to copy the waveform from one channel to the other, which was my only reason for wanting to have Separate Channel Editing functionality.
I have somehow made a recording which has recorded on one channel only - maybe my microphone wasn't fully plugged in when I made the recording, I don't know. But apart from the fact that it has only recorded on one channel , it's a good recording, and very important to me, so I urgently need to copy the waveform from one channel to the other, so that the sound will play out of both speakers and not just out of one. Surely this must be possible? But I can't see any way to do it. Please could someone help urgently.
Thanks
Dave