Can someone help with this philosophical problem I'm having.

So I keep thinking about how at some points during the day I think in a certain way and believe certain things, then at others I think and believe something entirely different.

So this has spent me in to a spiral of a problem. If outside influences such as alcohol etc can actually change the way we are/ act, then surely we are not actually in conscious control of ourselves. How can we be essentially different people from one moment to the next and still be the same conscious person.

For example I am told that I am the way I am due to a chemical imbalance in my brain due to anxiety. However, before those chemicals got muddled I was a completely different way. So surely it's the chemicals that are the thing in control and not me, the outside influence. That's why I used alcohol as an example, because that is a third party thing that can literally control the way we think, so how are we in control if basically a load of third party influences are the things that control us and can literally change the way we think?

I hope that made sense.