depends on trigger options.
yes, there's a bit problem with triggers, there's a trigger action where u can change the difficulty of the map as well, it can only work at the beginning of the map, (AI Difficulty) (1 = easy, 2 = normal, 3 = hard).
However, no "
impossible" difficulty option.
so, even if u already selected the difficulty that u want, it will be changed on some specific maps automatically by triggers, and it might affect any other maps, but don't worry if ur not using auto-selection then it's fine.