My dd is 14, fifteen in three months time. She is all over the place ! Very, very condescending and rude, particularly to DH, then apologises and is her old nice self for a day or so, then more stroppy, ungrateful, entitled behaviour. I feel as though I could and should be dealing with this more effectively. DH is upset as she is so unpleasant to him, and he has had a very tough year (bereavement).
She has had her ‘phone taken away for rudeness, door slamming etc, but it seems to make no difference. Her take on this is that confiscating her ‘phone doesn’t improve things, and that if we just left her alone and imposed no sanctions, that she would mull over her behaviour, feel guilty, apologise etc, whereas taking it away makes her angry and resentful. 
She is very well behaved at school. She is at her worst in the mornings, but getting her to sleep on time causes arguments each night as she wants to stay up later and not be treated “like a little child”. If she does have a late night she is horrible for the next few mornings. She has a medical condition which makes her tire more easily, and can affect mood, which doesn’t help.
I am stressed by all the conflict on top of a very difficult year. I need the wisdom of mothers of older teenagers !