Move on Dark can' be selected

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I have been plotting a show and found that I couldn't select "Move on Dark". It appear that at some point earlier the playback setting had been set to "General". Having plotted the show found that I needed Move on Dark but each time I made the change in Playback Defaults and saving it and closing defaults, the next time I looked in Playback Defaults it had been changed back to "General"! Any ideas why I can't select Move on Dark after plotting a show?

I have also had a problem with another, the Colour fade time default, this had been set to 3 sec. Again after plotting I found that I needed to change the time to 0 secs. This changed on the Q stack page but had (D3.0) on the Q line as well as 0.0. It appears that the default was held and was overriding the 0.0 setting I had entered. To get the fade to work as I wanted I had to deleted the Q and reprogramme it with the Colour fade time as 0.0. The (D 3.0) was removed and the fade working correctly. Again any ideas on what was happening here. 

I'm not sure if these are related problems or separate