The KJV was the standard for English speaking people for about 300 years. In the last hundred years, it has been attacked. Critics came out and did new textual research. They came to the conclusion that the KJV is not trustworthy. They mark certain words, phrases, verses, and even entire sections of some chapters as being in doubt.
God promised to preserve His Word. He did that, even in the last 400 years. He preserved it in Hebrew, Greek, and English. The KJV (Authorized) has been supernaturally preserved by God. He preserved it because it is without error. If you think there is error in it, then you misunderstand it. Sometimes God intends two meanings in the same word or phrase.
You can trust the King James. You can memorize it and know it is without error. Any version that removes God's words or verses from God's word is untrustworthy.