It can be confusing for some people to use words that are highly similar to each other. Personal is known to be a word that you can use when you are referring to the ownership of just one person. For example, you can say that an item is your personal hand sanitizer because this is something that you own, and you do not share it with anyone else.
When you say personnel, this is different. This refers to people who may be employed by a company or an organization. These words both come from the same Latin word but they have been derived a bit in order to form words that may seem similar but come with different meanings.