"Please explain" or "explain please"
Solution 1:
Both
Please explain
and
Explain, please
are grammatically correct. However, the former is vastly more common, and more to the point, it is also quite a bit more polite. Putting the please at the end makes it obvious that this is a command; putting the please first makes it more of a request.
Solution 2:
You can write "please explain," or "explain, please."
I prefer "please explain," but that is just a matter of style; both the phrases are perfectly fine.
Solution 3:
An adverb (please) may precede or follow the verb it modifies, so either would be correct, though you would probably want a comma for the latter:
Explain, please.
However, as you can see from this nGram, please explain is far more commonly used.
Solution 4:
I would say Please explain
is more suitable here. Not that I know so much about it but that sounds more appropriate for me to use please at the end of the sentence when I am using it with a noun;
Licence, please.