Girls, hello ? I want to ask, according to norms, what should a chair …

Girls, hello ? I want to ask, according to norms, what should a chair be like in our age? My son has a yellow stool, but it's somehow chubby, even when I wipe his bottom, the fat feels, it only washes off with soap :( Is this normal? They say that a normal stool should be liquid. We are completely on breastfeeding, I don't keep a diet, I just don't eat spicy and salty. Tell me please. Thank you for your answers ?