I read the topics that talk about how to cite people but am still a bit unsure what to do in this situation. I apologise if it's too similar to the other threads.
I'm writing my MSc thesis at the moment, and Googling for things I'm stuck on has led me to a lot of threads on this website which were useful to me. It seems like a lot of people are working through the same papers that I am reading. Almost always it was the same person (who has no contact details on his profile) who answered all the questions, so would it be sufficient if I acknowledged him via something like "I also want to thank (first name) (last name) for their work at " where  cites MSE. I would put that in my acknowledgements.
I know my advisor would really not like me to reference an online forum so a link to individual threads would be difficult to do.