How can I use outliner dots(?? I don't know it's name)? https://www.youtube.com/watch?v=z11Sv_kkoUs
In this video, I saw dots which can make me switch object to other not in object mode.
But I don't know how can I activate the dots.
Please let me know that.
I use 2.90.1 ver.
Mode toggling is a 2.91 feature. You need to update your Blender version.

Move mode toggling to the left column. When in non-object modes, icon buttons are shown in the left column for toggling modes. Clicking a dot icon will switch that object to become the new active object, Ctrl+click adds the object into the current mode. (2110af20f5)