PhD application: bad grade in relevant subject at master's
I believe it is very normal to have some drawbacks in every university experience, especially in the situation you described. I believe most people would be understanding if you explained to them what caused that specific grade (the changing masters and countries, etc), and I would explain how you are improving (extra hours of study, asking for advise of older students, learning better organization techniques, things of that kind). It's all a matter of how you expose the situation; if you expose it with a positive output, they will get a positive impression of you!
For my master thesis internship interview, one of the topics I talked about was how I in one semester had very low grades (average of 13/20) and even failed at one subject, and how I decided to turn things back around, got up on my feet and in the next semester, did one extra subject and ended with an average of 18/20, and they loved it, I was actually their first option for the internship! It's all about how you deliver the info :)