This is a great question!
As you know, there are different dispensations in Scriptures. God's name is "I AM!" (Exodus 3:14) That means HE can be whomever HE pleases, simultaneously if He desires! As we all know, God is a Spirit! Therefore, HE is in ALL places and in ALL people (who believe) simultaneously! Think, How Great He IS!
However, when He manifested Himself in the flesh, His Name became JESUS! Bare in mind that He is in ALL places simultaneously for He is "I AM!" Therefore, as "I AM" was walking around on the earth, in the NAME of JESUS (John 1:10) He was in heaven as well (an audible voice from heaven, The Spirit, Matthews 3:17 and a dove, The Spirit)!
You also know that He was born Jesus and came into the world to fulfill the law and to give His life for the remission of our sins! When he arose (Matthew 28:18 He said "...ALL authority is given unto me in heaven and in earth." Well, if "ALL authority was given unto JESUS," where was God? (Can't you see that Jesus and God are ONE?)
In the dispensation that WE currently live in, "I AM" is operating in the GLORY of JESUS gathering the Church! I Corinthians 15:24 says, "Then comes the end, when he delivers the kingdom to God the Father..." Do you see how "I AM" operates in as many GLORIES, simultaneously as He likes, but in the dispensation that WE live in, His Name is JESUS!
This is a great mystery! Therefore, His NAME "IS" mentioned in Scripture, but He is now operating in the Glory of JESUS which is mentioned numerous times throughout the Scriptures!