According to the Watchtower, the Catholic Church is a huge part of Babylon the Great which is led by Satan and his demons. Raymundus Martini, a Catholic Monk (who "represents" Babylon the Great to some extent), woke up one day in the 13th Century and decided to alter YHWH so it can be easily pronounced. Hence the SPANISH-ish version of YHWH was created... Jehova... (sounds something like this in Spanish: Heh-O-Va)
Chevelle,
Isn't that true for every other name that appears in the Bible? All the Hebrew names of the Bible were latinsed during the middle ages by Catholic churches or other groups where Y was being replaced by J. Yeshua, became Iesus and then became Jesu / Jesus during the use of the King James Bible in 1611 and thereafter.
All the names in the Bible that are now used are not the original pronunciations, but the English language versions of those. Not sure why Jehovah should be treated differently. Biblical names evolved and were latinised during the time when Catholics were a majority and that why the Latinised names have come from them.