The problem is that you have not clearly explained yourself. So, I am going to guess at what you are talking about
You had an existing table and then you added a new column and set it to Auto_Increment. When you do this, you need to MANUALLY set the Auto_Increment value on all existing data and then MANUALLY change the Next Auto_Increment value to the actual next value.
If you have an existing table with data, you need to determine the ID of the row you want to update before you actually update it, otherwise your query will insert a new row or fail for having more than 1 match.
I do not browse the forums regularly anymore. If you need me for anything (asking questions or anything else), then PM me (be descriptive in your PM, message containing only a link to a thread will be ignored).