can we go back to the old post time ident? I found it much easier to see which were new posts

Bob, It wasn't anything I've changed, so was confused when I saw it was different for me the other day.
Try this
Click on your profile, scroll down to date and time format, and change that to what you want. Even if it is currently set how you want, change it, save and change it back again.

Thanks Ali, it has gone back to the way it was for me too