Questions about the Laws of Theft

A few questions regarding gezel:

1. A few years ago, someone asked me, as a graphic designer, to forge a student-verification document for her sister. Afterwards, I realized it was probably for getting a student discount on a Rav-Kav. Did I trangress the prohibition of gezel? And how can this be corrected?
2. I registered several times for a student Rav-Kav and even paid for “studies” that I didn’t actually study. Is that considered gezel?
3. I worked at a newspaper, and they had fonts, typefaces that maybe someone had installed on the computer without permission (since they cost money). I used those fonts for the newspaper’s work so maybe it was gezel?
4. I once made a presentation for a daycare, and they gave me many songs they had to include in the presentation. Was I allowed to use those songs? It’s possible they legally purchased them, but I really don’t know.

I would appreciate if you could please clarify these issues for me. 

Thank you very much.

Shalom uvracha,

Regarding questions 1, 3, and 4, there’s no reason to be concerned that any improper use was done.

As for question 2, if you registered for a place where you could have studied material that grants a valid student certification, then it’s permitted to use that certification, even if in practice you didn’t end up learning it.