Apologies again BJS Hope you found a way around the subtitle problem.
hc, I get back home, re-read those instructions, then see an issue.
The first instruction is to ensure the Chromecast is on the same WiFi as the tablet. But the Chromecast issue is that it is on my woman's WiFi and I'm now at hope. Whoops. But it seems problematic anyway as it seems to suggest the WiFi to be used has to be available in the same location as the WiFi it is already on; which can't happen.
Found the small button (hard to spot ain't it) and will try that in a while.