You: Wash the vulva with light salt water, too. Don't wash frequently with any cleaning liquid or soap or shower gel, which will change your (especially girls') pudendal beneficial flora.
If the surface of a boy's glans is itchy with peeling or white dirt, after cleaning, apply it with Pikang cream (which is not expensive in pharmacies, I don't know what its scientific name is) and massage for one minute, once in the morning and once in the evening, for three consecutive days. Not yet. I need to go to the hospital to see a dermatologist or urologist.
If the girl's vulva itches, it will be fine to wash it with salt water for a few days. If it has vulvar itching, she needs to go to the hospital to see a gynecologist and do some tests. If you have these problems, you can't have children, so don't leave semen in the vagina.