Different spot ID in each frame

Hello,
I am using ImageJ to track movement of particles across a channel with an end goal of finding the velocity. When I track these particles in ImageJ, each particle gets a new spot ID in each frame, making it very difficult to find the velocity because I will have to sort through every ID and figure out which ID belongs to which particle. Is there a setting I am unaware of or something I may be doing wrong that is preventing the spots from only being recognized once? See the images below. image image
Thanks!