Sony head unit forgetting some settings?

[MJNewton]

The Sony head unit in our 2013 Fiesta Titanium appears to be forgetting changes to various settings made from time to time. For example, if I change some of the sound settings (treble and bass etc) or the Adaptive Volume setting then they will apply, remain after a power cycle but then at some point in the future I am finding they have set back to default!

I am aware that some settings (e.g. treble/bass/etc) are source specific (they are even different for DAB and FM) however I am seeing this issue arise even within the same source. No other person could be changing the settings without my knowledge and I can also confirm that other aspects that need memorising such as tuned stations are all remaining stuck and so I am not suspecting it is a (lack of) permanent live type issue.

Has anyone ever witnessed similar issues and/or know what the cause and solution might be? At the moment I am just putting it down to the general crappyness of this particular Sony system but even so I would have expected others to have mentioned this in the past but I have not found anything in the archives.