Where did my lock arrows go?

Hi guys,
I recently updated to 2.8 and I’m still struggling a bit with the Interface.
I wanted to lock my background images but the arrow disappeared.
How can I lock the collection?

Unbenannt

You just need to show/activate it via the filter first (top right).

filter2

Other visibility controls now grouped in the filter.

Click the funnel icon and select the filters you want to display.