Shower on Yom Tov

Hello, is it permissible to bathe a baby and can an adult take a shower?

I am copying for you the instructions of my teacher, the Gaon, Rabbi Avraham Fried, shlita, on this matter:

Laws of Bathing on Yom Tov – Summary of Permitted Methods:

Bathing the entire body in cold water [for Ashkenazim only in cases of distress] - is permitted as usual.

Bathing in hot water:

A] Bathing the entire body together – is prohibited for Ashkenazim in any case, and for Sephardim, it is permitted only in water heated before Yom Tov (such as placing a pot of water on the fire before Yom Tov and removing it from the fire before Yom Tov begins, or even removing it on Yom Tov itself. Also, if cold water is mixed with hot water that was heated before Yom Tov).

B] Bathing the body limb by limb [i.e., with drying after each limb that is washed] – in water heated on Yom Tov is prohibited, and in water heated before Yom Tov is permitted, and for Ashkenazim only in cases of distress [therefore, one can place a pot of water on the fire before Yom Tov, and on Yom Tov pour it into a bathtub, add cold water, and bathe in it].

C] Bathing the face, hands, and feet – is permitted even in water heated on Yom Tov [therefore, one can place a pot of water on the fire on Yom Tov, pour it into a bathtub, and add cold water. However, bathing in water from a solar heater [without closing the cold water tap entering the heater] is not preferable, as in the next section].

D] Bathing a minor part of the body – is permitted in water heated before Yom Tov, and one who is lenient to bathe in water heated on Yom Tov by a pot on the fire or by an electric boiler [that was on before the holiday or by a Shabbat timer], has what to rely on [and if one wishes to bathe in hot water from the solar heater, one should initially close the cold water tap entering the heater, but one should not protest against one who is lenient in this even without closing the cold water tap of the heater].

Bathing a baby

A] A baby who is not accustomed to being bathed every day has the same law as an adult.

B] The law of bathing the entire body of a baby who is accustomed to being bathed every day, as well as cleaning dirt from a baby [even if not accustomed to being bathed every day]:

Is permitted in water heated before Yom Tov, and even in water heated on Yom Tov by a pot on the fire is permitted, provided the water was heated for drinking or dishwashing [that is, place a pot of water on the fire, use part of the hot water to wash dishes, and pour the remaining water into the bathtub, add cold water, and bathe the baby in it].

Bathing in hot water from the solar heater [without closing the cold water tap entering the heater], is not preferable, and one who is lenient in this by opening the tap for drinking or dishwashing [such as after opening the tap, washing a few dishes in the bathtub, and then bathing the baby], should not be protested against.