why do I automatically select all the tracks, how to disable it?

What does this sign mean in the upper right corner, why do I automatically select all the tracks, how to disable it?
Снимок экрана 2020-04-22 в 16.42.32.png

This sign is grouping Edit/Group (default: CTRL+G) if you want to turn it off you go Edit/Ungroup or CTRL+U

Cheers