FlashPlayer and Firefox

Problems with using FlashPlayer with Mozilla Firefox

I currently use a desk top PC and I have Flashplayer 24.0.0 and my default browser is Firefox 50.1.0

My problem is with using BBC iPlayer or ITV Hub.  With Flashplayer newly installed , I can get either BBC or ITV. However , neither BBC or ITV are available after my PC has been closed down and re-started. If I then re-install Flashplayer , BBC and ITV become available again.

If I change my browser to Google Chrome , I don’t have the same problem and both BBC and ITV are available all the time.

I prefer Firefox to Google Chrome but what is the compatability issue  between Firefox and Flashplayer. Is there a way round it ?

Regards

Terry Dennis