Try holding the bottle of drops in your hand for a few minutes to warm it up then once you have put the drops in, massage underneath the ear opening to distribute it.
Agree with above. It's possibly a temperature issue. But even if it's not, getting liquid in their ears is not an experience any cat relishes. I wonder if you could apply the drops on the inside but just above the ear canal opening. He's going to shake his head when you release him anyway. This might allow you to get all the drops at the door-step and then he can shake them inside.
But yes, I would fill a small cup with warm water and let the bottle sit inside it for a few minutes. Just up to the neck in case the cap isn't firmly on.