To make use of more than one Live MetaTrader account and be able to switch in between them, follow the steps below

You need to:

Click/Tap on "File".

Click/Tap on "Login to Trade Account".

Enter the login information of the new Live Account that you wish to log into.

Click/Tab on "Login".

Your newly added account will be visible in the "Accounts" sub-section in the "Navigator" section.