FOR THE PLAYER:
This is in the config file. You must change the player there. This is set up for Foobar2000 but it works with iTunes and Winamp as well. See below for Foobar2000.
; For a list of valid Player= values, check: http://rainmeter.net/RainCMS/?q=NowPlaying_beta#playerlist
Player=foobar2000
; NOTE!
; If you're using foobar2000, you must download the foo_rainmeter.dll plugin for foobar2000
; from http://rainmeter.net/RainCMS/?q=NowPlaying_beta (under 'Supported players').

FOR Gmail:
This is in the config file
; Edit your username (without @gmail.com) and password here.
; dont forget to create an application password if 2-step security is enabled.
UName=
UPass=