"Stoler" or "at stole" means "to trust."
"Tror" or "at tro" means "to think" or in an easier sense, "to believe," "to predict."
I can see why you'd get confused between the two, since in English, you can "trust" or "believe" in someone, but "tror" is more of "to guess."
For example, to correctly use "tror," you would say:
"Jeg tror bogen er godt." = I think the book is good (but I haven't read it yet!) or, I believe the book is good.
And to use "stoler," you'd use it like this:
"Du siger, at bogen er godt, så jeg stoler på dig." = You say that the book is good, so I trust you.
Think of it like this:
You cannot "tro på nogen," or "think on/in someone."
But, you can "stol på nogen," or "trust in someone."
I hope this clears things up. If any of the sentences in Danish are wrong, please correct me! I am not a native Danish speaker, nor am I fluent in it. Thanks!