Questions about the Laws of Theft

Several questions regarding theft: 1. A few years ago, someone asked me, as a graphic designer, to forge a study certificate for her sister. Later, I realized it was probably for a student travel card. Did I cause theft? How can this be rectified? 2. I registered several times for a student travel card and paid for studies that I did not actually attend. Is this considered theft? 3. In the past, I worked at a newspaper, and there were fonts there that someone might have installed on the newspaper's computer without permission (because they cost money), and I used them for the newspaper. Should I be concerned about this? 4. I once made a presentation for a certain institution, and they gave me many songs they had to include in the presentation. Was I allowed to use these songs? They might have bought them at full price, but I don't really know. I would appreciate help on this matter. Thank you very much.

Hello,
1. 3. 4. There is no reason to worry about improper use.
2. If you registered at a place where you had the opportunity to study real material that grants a study certificate, it is permissible to use it for a study certificate, even if you did not actually study.