Unable to change overlap of colored lines

I would really like some help. I'm working on a project that has colored outlines to the characters. Because I can't share a picture, this is a simplified version of my problem. Lets say I created two straight lines overlapping each other to create a plus symbol. Then, I changed the color of the vertical line to blue and horizontal to red. The problem is, I would like the red line to appear to overcross the blue, but instead, the blue is overcrossing the red. I've tried making a new red line directly overtop, but it just gets put under. Please, if I could get some help, I would be so thankful ;_;