Formality

I’m also struggling with that in many contexts. I recently got to find out that a former classmate of mine was convinced I didn’t like her… She is one of the few I’ve always respected and liked very much. So… yeah. 
But it’s even more difficult in a more professional context. For instance, I avoided using personal pronouns when talking to my elementary school teachers. In German we differentiate two forms of “you”. The formal form being “Sie” and the informal one “du”. The problem is that in my elementary school many teachers were quite relaxed concerning those pronouns so most people said “du”. But I felt like this was wrong because the general rule is using “Sie” when addressing a teacher and nobody ever said something about this matter officially. It was so weird for me so I successfully avoided this insecurity by just calling them by their names when asking something (e.g. “Excuse me Mrs Miller, I’ve got a question. What does that mean?”)

It got a lot easier later on because then it was clear that you had to use “Sie”. However, there are still multiple occasion when things like that occur and everybody but me seems to intuitively know, what to do and say. 

Just taken me back over 35 years to O-grade German at high school in Scotland

Just taken me back over 35 years to O-grade German at high school in Scotland

I’m sorry you had to endure that.  Even as a native speaker… German is not fun and most people use really sloppy grammar because they don’t know any better. Nobody is able to make any sense of those grammar rules.

Me too! I think I’d struggle with Sie vs du as well.