Well, she is older than me with 4 years anyway,we were watching a singing competition and I started singing along with a lousy voice.. my sister was so angry and yelled at me.. forcing me to go to my room... I want to apologize but.. I don't want to make it so clear.. (we have a complicated relationship)

Sometimes sisters just get annoyed with the younger siblings I have 2 sisters myself. Step 1 just let her cool off trust me in a day or two she won't be thinking about it. If and it's very unlikely that that doesn't work just sit down with her and apologies maybe agree to do something for her if it's really bad :) I hope it works out.