Object doesn't rotate around its pivot in Sequencer

I solved this problem. Set pivot object center. Select this asset at sequancer. The asset > transform > edit selection Check ‘Use quaternion interpolation’. That worked for me.

What are you saying?

“Set pivot object center” Is this a direction? Can you say how?

“Select this asset at sequancer.” … WHAT ASSET? What are saying?

“The asset > transform > edit selection” … What?
Where do you get to this quaternian thing?