If you have SharePoint configued to use NTLM with Integrated Windows Authentication (IWA) then it can be tricky to come into your portal as someone other than yourself. There is a cool way to force SharePoint to present a login prompt to check your credentials again. This is very useful especially when you are trying to test with other accounts.

The trick is to append:

 
/_layouts/15/closeConnection.aspx?loginasanotheruser=true

to your site collection URL. So if our URL was “http://yoursharepointsite” then the example would be:

 
http://yoursharepointsite/_layouts/15/closeConnection.aspx?loginasanotheruser=true

Hope this helps, questions are welcome.