why can't I see all the songs I bought on iTunes in the past
why can't I access all the iTunes I bought on my Apple ID same ID but different password
Question marked as
Main reasons are:
If you have changed countries then old purchases won't appear: "Change your Apple ID country or region" click here --> https://support.apple.com/HT201389
"Redownload your apps, music, movies, TV shows, and books on any devices that you might use to play or read them in the future. That's because some types of content might not be available in your new country or region. (Learn what types of content and services are available in your new country or region. - httphttps://support.apple.com/HT20441
and this one hidden away deeply in legalese:
http://www.apple.com/legal/internet-services/itunes/us/terms.html - "Content may not be available for Redownload if that Content is no longer offered on our Services."
and:
If there's an issue when you redownload apps, movies, or other content from Apple - Apple Support