Isaiah 48:16 declares,
"Come near to Me, listen to this: From the first I have not spoken in secret, From the time it took place, I was there. And now the Lord GOD (God the Father) has sent Me (God the Word who became flesh - John 1:14), and His Spirit (God the Holy Spirit)."
The three Persons in the ONE Godhead are clearly seen in this OT verse. The interesting thing that I have just seen in this verse is that one speaking (Me) refers to God as "Lord God." The title "Lord" refers to position in the Godhead, not to the fact than any of the other persons in the Godhead are not fully God.
Now let's look at Acts 2:36,
"Therefore let all the house of Israel know for certain that God has made Him both Lord and Christ--this Jesus whom you crucified."
After the resurrection and exaltation of Jesus to the right hand of God the Father (verse 33), the position of "Lord" in the Godhead was then given by God the Father to Jesus!
This better explains Phil 2:5-11 where it says,
Have this attitude in yourselves which was also in Christ Jesus, who, although He existed in the form of God, did not regard equality with God a thing to be grasped, but emptied Himself, taking the form of a bond-servant, and being made in the likeness of men. Being found in appearance as a man, He humbled Himself by becoming obedient to the point of death, even death on a cross. For this reason also, God highly exalted Him, and bestowed on Him the name which is above every name, so that at the name of Jesus EVERY KNEE WILL BOW, of those who are in heaven and on earth and under the earth, and that every tongue will confess that Jesus Christ is Lord, to the glory of God the Father.
Blessings