Ps 40: 7 "to do your will, O God"; Which "God"?

 Is Jesus God?

Ps 40: 7 NWT

“In view of that, I said: “Here I have come,

In the roll of the book it being written about me.

8 To do your will, O my God, I have delighted,

And your law is within my inward parts.”

Heb 10:5-7 NWT

“Hence when he comes into the world he says: “‘Sacrifice and offering you did not want, but you prepared a body for me. 6 You did not approve of whole burnt offerings and sin [offering].’ 7 Then I said, ‘Look! I am come (in the roll of the book it is written about me) to do your will, O God.’”

“…to do your will, O God” Ps 40:7

“…to do your will, O God” Heb” Heb 10:7

Question:

If Jesus is “God”, then just which “O God’s” will is the God Jesus wanting to do?, Just who is this other “God” i.e. “O God”?

NB,

Other translations read similarly!