I just upgraded to 2.7.1.
I wanted to change the default name for the PAGE widget. It was in Side bar 2.
I did make the change... so I thought, but when I wanted to navigate away from the page, I was told to save the changes by pressing Save Changes at the bottom of the widget column.
There WAS NO "SAVE CHANGES" button at the bottom of Side bar 2. There is one under Side Bar 2.