I still have the P900 but do the same as Owene. I’ve put the Birdwatching programme into the Scene on the selector wheel, so I don’t have to keep looking for it, if I want to switch to something else, like night sky.
If I struggle for focus on a very high bird in flight, I find something solid, like a tree in the distance and focus on that, then hold it till I find the bird again. With practise it works very well. Though somehow, switching to Video I don’t need to do that, it just seems to focus on everything LOL.