I take it from your post that you want your dad to do something. Something like stand up and admit that he has a problem and seek help for it. However, when you are talking about "Alzheimer's" that's exactly what he WON'T DO.
It's sad but true that this is the very nature of this awful disease. It's not that your dad forgets, as much as it is that he forgets that he has forgotten. So to him, there is probably something much more wrong with you, than with him.
When you study and learn more about this disease you will learn that it is not always necessary for him to know what is wrong; but, for you to know is imparative. And, all the while you will be working hard to reassure him that everything is "OK". Because in the end, everything IS REALLY "OK". After all he still loves you and you love him and will make sure that he is safe and cared for and made to feel comfortable and happy, (as he can be with this awful disease). And, that is all you can do. But God know's, that that will be enough for anyone to have to cope with.
Remember that we, none of us, can change others. But in the end, change in ourselves is everything.
Hugs on your journey,