How do I change my display photo on Tumblr?

Since the dash changed, I haven't been able to change my display photo on Tumblr. When I go to my blog & to "Customize," and then to "Info," all that's there is my blog title and description. The place where I used to be able to change my display photo is no longer there. Is this just a problem with my computer/internet/Tumblr, or did they change it and not tell me? Any help is appreciated, I would give you a promo for answering or something but I don't have enough followers to make much of a difference, lol. But I'll totally follow everyone who submits an answer, if you'd like :)