Changing instrument

Hello
I would appreciate some help on the following:
I have written a staff for a Bb clarinet. Being a transposing instrument, all “written D” notes sound as C's and so on.
I have now decided to use violin instead of the clarinet.
What steps do I have to use in order to have the notes transposed down by a major 2nd (since violin is a non transposing instr.) and still sound as they did?
I right-clicked on the instrument name (at the beginning of the staff), then clicked on “Staff properties, and chose violin instead of clarinet. As a result, the notes were all transposed down (correctly), but they keep sounding a major 2nd down. I mean that D’s (that sounded as C’s) have turned to C’s but sound as Bb.
So, what do I have to do to get things right?

Thank you in advance.