Tooltip of record actions

You can edit tooltip by changing the description of record action.

Just to clarify - by tooltip here I'm assuming you mean the label that shows when you hover over a button? If so, that is just the description of the action. You can configure it in the record type designer where you set up the record action.

I don't have description part in my edit Related Action 

screenshot?

You need to change the selection for Display Name to any of the other two options. When using process model name as display name, the record action description is set by default to process model description.

You can either change the Display name selection or edit the description of process model which you are using for action.

Thanks Tooltip  is coming from Process Model description

Thanks for confirming, would be great for you to verify the answer if it helped