Having set up your SignUp/SignIn box to show your site logo (see intructions) - now you have logged in you may want the Sign Out box to have the same appearance ...

First go to Dashboard and add to Appearance:

(if you want to have the same background colour)

#xg_module_account .account-links{
height:auto;
background:#990000; 
}       (using the same colour as your SignUp box)

(if you want to add a hover effect )
#xg_module_account .account-links:hover {
background:#fff;
}

(if you want to remove the member name above Sign Out box)

#xg_module_account .xg_module_head {
display:none!important;
}

Then, to add the site logo to the Sign Out box, go to Language editor and search for 'Sign Out'

find the text 'Sign Out' (should be the second instance of this text) and insert your image <img src="Your Image URL" /> - so you will now have: 

<img src="Your Image URL" />Sign Out

Here is the appearance on my site:

Sign in:

Sign out: