My debugging always stops at this line 1989 that has a blue right arrow. I thought it should only stop at those with the red check (line 1987).
How can I add/remove the blue right arrow?
That icon just indicates the current line of execution. As you step through the program, that icon will move with the line of code being executed.
If the program breaks at a point near where the break point is, but not exactly there, then there are typically two causes in my experience.