Watermelon Automatic RSQ 1st grow

Im new to this world and this is my first grow, i would appreciate if someone gives me some advices, actually i think something went wrong with the germination, cause 2 plants had the roots too high, i had to plant them earlier, for the third (the one with the different pot) went different and is actually more smaller and its growing properly, and so the others. So thank you if someone help me through the journey