I saw an article once on this, the guy said that there's only one way to hold a uke (his way), and you do it that way either standing or sitting. Well, heck. I have a soprano, a concert and a banjolele and I play 'em all differently and I don't like playing while standing but I can do it. Whatever works best is best. Ukes are pretty easy to hold for the most part, you realize this if you play something like a balalaika or a sanxian or a rawap, if you hold them wrong you either can't work the strings, you muffle the soundbox or you scratch up the expensive skin, in the case of the balalaika it'll stick you. I usually rest a uke on my right thigh while sitting, that's it. I can't hold it like the guy in the article, either his uke is microscopic and / or he's huge.