Thanks, I've spoken to DB and he's going to call in at mum's house tonight and do whatever needs to be done. She's far less likely to be cranky with him as he rarely visits and she is always delighted to see him.
On my remote control there is a MENU button. This allows you to scroll through the settings - adjusting colour, brightness etc and sound. I think you can choose what is effectively the default setting. If when she switches on, she can't hear, she can increase the volume but only as high as the level you set.
She might still not hear well and become very annoyed with you if she knows what you did!!
When I phone my Mum she spends ages trying to find the mute button and sometimes gives up completely - so we have to talk with the telly on, very loudly, in the background. She only needs to change between 2-3 channels, switch the sound up or down or off completely. The controls are far too complicated and she can't really see the writing on them any more.
She does have the sound up far too high, and we're trying to persuade her to get hearing aids.
The idea of a fixed setting - sort of "cruise control" - would be great. I wonder how you can set that...
There is a setting somewhere to set it at whichever level you want as you turn it on but trouble is that won't stop her turning it up again if she thinks its too quiet. Maybe a letter from the local council about unsocial levels of noise would make her see sense.