You can change items conditionally to non logged in and logged in user. See in the snow theme
Function nav_user_search() there you will find condition like if (!qa_is_logged_in()) around line #69 this containing login form and display only to non logged in users.
To switch display for logged in users you need to check wether user logged in or not same you can find in Snow theme around line #92 function is looged_in() in that find condition if (qa_is_logged_in()) now in this condition you can place whatever you want to display to logged in usres.
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