Also you can have a puppy that one or both ears come up then two days later one is down
That is usually when they are teething. Also when you are looking at your puppy you can usually tell if they will come up you will see an arch from the ear starts at the head that is a good sign that they will come up. If the ear is really flat to the head you might have to work at it. I use treats and toys to get them to look up at me and get excited so when they tip there head up to look at me I can see if they stand that way also (Gravity LOL ) But that is a good sign also~