The tragedy of JWs is that although they frequently use an Anglicized transliteration of the Hebrew letters YHWH, thinking this identifies them as the only people God is pleased with, the sad fact is that virtually none of them can call Him "Father" in the sense Jesus meant.
That is because Jesus said to pray "Our Father who is in Heaven" to Jewish people who already were in covenant relationship with God as their Father. YHWH had 'fathered' them as a nation, 'birthing' them out of obscurity and slavery in Egypt at Mt Sinai when they became His covenant people. They understood that concept and how it applied to them. It didn't apply to the pagan nations. Jesus came to fulfil that and to introduce the New Covenant for Christians, who would be adopted as God's spiritual children - John 1:12-13 & ch. 3. All such can address God as their Father - Abba (Romans ch. 8 first half.) That is the point, which JWs completely fail to understand.
What's the use in calling God "Jehovah" if you can't call Him "Father"? They teach that only 144,000 humans can ever call God "Father" in that biblical sense of those who are in the New Covenant, adopted into God's heavenly family. As virtually no JWs today either were in the Mosaic Covenant, or are now in the New Covenant, they cannot call God "Abba - Father".