General tab menu settings.
Clicking this box activates xpSticky.
Set at Independent, by default.
You can change this to Action-Controlled.
In this mode, particles will be affected if they come into the field of effect of the modifier.
When in the Action-Controlled Mode setting, the modifier will only act on a particle when told to do so by an action.
This is the probability that a particle will stick to an object if it comes within range.
If it is set to 100% the particle will always stick; if it is 0 (zero) %, it never will.
Animation to demonstrate the effect of Probability set at 100%.
By comparison, Probability is lowered to 5%, in this animation, with less chance of particles sticking to the scene object.