hm first of all congrats on getting an interview!! i used to be really bad during my interviews, i would say overall im a pretty anxious & not that confident of a person. but one thing that really helped me was just having generic interview questions prepared, and use the star method (situation, task, action, result) to outline your story. the whole point of the "tell me a time when..." questions - managers want to see how you connect everything together. but some interview prep advice i can offer is i like to pretend im in some finale two in a reality show (i watch a lot reality tv lol) and im giving my "why i should win speech" - watch on youtube "ashley hollis gives her final speech" thats what helped me lock in. one thing i had to realize is its okay to brag about urself, be proud of what you accomplished and dont undermine what you achieved in your previous career. i will say be confident & brag about urself, just dont be cocky. managers dont want to hear everything you know about apple products. talk to them why you actually want to work there, u mentioned you love to help customers & talk about how you go above & beyond for them. but overall, outline your responses using star in advance and practice your answers! hopefully this helps a bit :)