Glad you like the app! To answer your question: Tumblr allows you to create multiple blogs associated with the same Tumblr account. If you have multiple blogs, a list of them is available from the top left menu, which is labeled with the name of the blog you’re currently in. Of course, there is only one dashboard per Tumblr account (that is, per email address username).

Now, if what you want is to be able to switch between separate Tumblr accounts—say, between two friends sharing an iPad—then it’s very simple. Choose the “log out” button, then enter the information for the account you’d like to use. When you want to switch back, just log out and log back in. Hope that helps!