isn't trying to change one's own beliefs a bit like trying to tickle oneself?

One somehow needs to present evidence to oneself that reinforces the target belief, in such a way that one isn't reinforcing the opposite belief through the very act of selecting the right evidence.

Perhaps it is only possible in general to weaken existing beliefs, by putting oneself into novel situations that have the propensity to challenge one's existing beliefs to a certain extent.

If I ask someone if they believe there is an even or odd number of gumballs in the jar, what I mean by that statement is do they have conscious confidence that it is true, not whether or not they have conscious confidence that it is likely to be true. If I was wondering about what they would pick because they are more inclined towards it because of brain mechanisms that they aren't aware of, I would ask which do you believe is more likely to be true or "oh you don't believe either is true? which would you pick if you had to pick one". This is generally assumed when we speak about beliefs. It's how we use them in a practical sense.

I don't really disagree with you when it comes to absolute belief. And sure this is a philosophy forum so we can get technical if you want.

I'm just saying that it if we are gonna tell someone that they don't simply lack belief because they have some belief in an absolute sense rather than the way we use the term in practical terms, then we might as well also tell people who claim to know something that they don't actually know it in an absolute sense. Or we can assume when someone knows something, knowledge is used in practical terms and belief is used in practical terms (the way we generally use the word belief).

So no I don't really disagree with you, I just think the way you use the word belief is different than the atheist when they say they lack belief. And if you want to get nitpicky with that, I don't see why you wouldn't tell people that they don't know every time they claim to know something. But generally people assume the word belief and the word knowledge are being used in a practical sense.