Sorry for the delay in replying to your suggestions. I am travelling again in the holiday season, and so I'm again trying to use my macbook to develop Android apps.
When I run ./adb devices -l, I see the device(s) OK - for example with my Nexus 7 tablet I see:
List of devices attached
<some sort of device id> device usb:24100000 product:nakasi model:Nexus_7 device:grouper
Similarly if I have an emulator running, I see the emulator listed.
Regarding the video, thanks, but I don't see anything that I'm doing differently, except of course that I have more recent versions of Qt, Android SDK, android NDK, java etc than in the video. Interestingly in the video, you can see the author also sees "unable to start <appname> " (as I do) in the application output window, but the app starts for him.
A recent query here by a user targetting iOS had issues deploying apps with QtCreator 3.5 which were resolved by using QtCreator 3.6 - I have just updated to 3.6 but I experience the same problems as before.
Thanks for any suggestions.