In the Old Testament the word "God" seems to be used fairly freely for each member of the Trinity, but in the New Testament that title/word normally belongs to the Father.
However, the name "LORD" or Jehovah/Yahweh normally belongs to the Son - and the most basic Christian confession is that "Jesus is LORD" - "Jesus is Jehovah/Yahweh".
Paul describes how the words "God" and "LORD" are typically (though not exclusively) allocated to the Father and the Son:
"for us there is but one God, the Father, from whom all things came and for whom we live; and there is but one Lord, Jesus Christ, through whom all things came and through whom we live."
1 Corinthians 8:6
Is this also generally true of the Old Testament also - as some of the early Church Fathers suggest?
The LORD/Jehovah/Yahweh throughout the Old Testament is normally God the Son as visible form of the invisible God or the Mediator - the One who the Father sends in the power of the Spirit.
Of course, we can find several examples where the word "LORD" refers to the Father and several examples where the word "God" refers to the Son (not least Hebrews 1:8/Psalm 45:6 when God the Father refers to Jesus as God).
However, this basic pattern seems to be important.
Jesus is Jehovah/Yahweh/LORD - that is our most basic confession, which can only be meaningfully confessed by the power of the Spirit.
Jesus is the God of Abraham, Isaac and Jacob - the One who met with Moses and the prophets.
The image is from Bill & Joan Cetnar from their 1982 book - "Questions for Jehovah's Witnesses" which no longer seems to be in print.
There is a very detailed blog from Stephen E Jones, a retired Australian, that is devoted to showing that Jesus is Jehovah - https://jesusisyhwh.blogspot.com/