I created new custom masterpage. But "Sign as different user" option disappear in WelcomeMenuBox.
is there a way to add this option, maybe i remove it by accidently?
By default in SharePoint 2013 there is no option for "Sign in as different user". Follow the below steps to enable it
Go to the location C:\Program Files\Common Files\microsoft shared\Web ServerExtensions\15\TEMPLATE\CONTROLTEMPLATES.
Here we have a file named welcome.ascx.
Step 2: Open that file and add the blow code
<SharePoint:MenuItemTemplate runat="server" ID="ID_LoginAsDifferentUser" Text="<%$Resources:wss,personalactions_loginasdifferentuser%>" Description="<%$Resources:wss,personalactions_loginasdifferentuserdescription%>" MenuGroupId="100" Sequence="100" UseShortId="true" />
Paste this code above the tag which has ID_RequestAcess.
Step 3: Refresh the site it will be available.