Hello and thanks for using Just Answer.
My name is ***** ***** am happy to assist you with your enquiry.
You ar eindeed correct- as soon as you have executed your new Will, your old Will automatically becomes revoked/invalidated, so anything you have put in your old Will is null and void and no further action needs to be taken.
Therefore, your old Trustee has no power to act, and whoever you have appointed as Trustee in your new Will has the power and duty to deal with your Estate.
I hope this clarifies the position to you.
Can I assist you any further?