I always judge the direction of current when I do problems, but I think the direction of current is the same as that of positive charge and the only direction of negative charge is the opposite. I am afraid of confusion during the exam. I can write the FBI in my left hand, F in my thumb, I in my middle finger and B in my palm.

I don't know what your problem is. You said that the definition in the book is not standardized, so you should add preconditions.