When King James of Scotland became King
James I of England, he held a very exalted idea of his kingship, and he preferred a High Church form religion, which used an eloquent and elegant translation of the Bible, in the best English style of the time. The Geneva Bible was translated by dissident Protestants who preferred a simplified, low-church type of religion, free of popish and elitiist ideas and practices. They also wanted an English Bible that spoke the way they did, and reflected their religious and political views. To that end, they also included marginal notes that were anti-monarchic. King James, of course, wanted none of that!
When James appointed a team of scholars to work on a new Bible, they didn't use the Geneva Bible as their basis, but the Bishops' Bible, which had already been revised in the 16th century. They were commissioned to make a version of it that was as elegant and accurate as possible, and to translate afresh where necessary in order in order to accomplish that. At the same time, the new Bible would have to be acceptable to low-church Protestants, so some of them were included in the team as well. But no notes were permitted.
Neither Bible is especialy accurate accurate in the terms of modern scholarship. The Greek manuscripts they used only dated back to the late Middle Ages, and the 16th century English scholars had a less than perfect understanding of Hebrew and Semitic languages, which even now present challenges to translators, both Jewish and Christian.
An additional difficulty arises from the fact that early Christians relied on Greek versions of Hebrew scriptures, which can differ from the Hebrew Masoretic Text. The MT was edited into its present form c.920 CE, and it is the basis of later Hebrew Tanakhs, like the versions used by 16th century scholars. The early Greek texts did not yet exist in a single authoritative edition, and were translated from earlier Hebrew versions that may differ from the MT. Both Hebrew and Greek books existed in the form of many separate scrolls, which were translated into Greek starting in the 3rd century BCE. The editing work of Origen in the 3rd century CE, and later Christian scholars, gave us the the editions of the Greek Septuagint familiar to scholars today, but both the Geneva and King James scholars didn't know about all of this.
The King James Version itself underwent revisions, and the version printed today is from 1789. In the 19th century, people realized that the English language had changed quite a bit, and a number of words didn't mean the same things they did in 1600. Among updated versions were the American Standard and the Revised Standard versions, making the language more understandable to people of the time, and reflecting the content of ancient manuscripts which had been discovered (and continue to be discovered).
Harry Freedman, The Murderous History of Bible Translations: Power, Conflict and the Quest for Meaning (2016) is a good overview of the topic, geared toward a general audience.
Adam Nicolson, God's Secretaries: The Making of the King James Bible (2001) was a best-seller focused exclusively on the KJV.