In the upper right corner of APEX 5 you'll see your login name and a rather anonymous avatar. Just for fun - and recognisability - you can add your own face there. Or a picture of your dog of you like that one better. Just click "Edit Profile" to upload a picture. O yeah - you can change your username and password as well in that pop up.
Way more functional is what's below the "Preferences" button. You can specify here how you want APEX to act when you press a "Run Application" button. You can define whether the Application should start in a new tab or in a new window. What's pretty cool is that when you keep that tab or window open and press the Run button again, focus will switch to that tab/window and your page will be reloaded there. So you don't get multiple tabs/windows, but just one. And the way back using the Developer Toolbar is also supported!
And if you're working on multiple applications at the same time, you'll love the last preference: You can even share that tab/window over multiple applications...
One small pitfall : the changes you make to the Prefences / Photo etc will be functional after a page refresh - but that's probably a bug that will be fixed ;-)