Sign in as different user
16/02/2016 11:07
Go to the location C:\Program Files\Common Files\microsoft shared\Web ServerExtensions\15\TEMPLATE\CONTROLTEMPLATES.
Here we have a file named welcome.ascx.
Put it somewhere between others SharePoint menu items
<SharePoint:MenuItemTemplate runat="server"
Text="<%$Resources:wss,personalactions_loginasdifferentuser%>"
Description="<%$Resources:wss,personalactions_loginasdifferentuserdescription%>"
MenuGroupId="100"
Sequence="100"
UseShortId="true"
/>