Have you changed your vote?

[ZenGum]

That's a different question I think.

Lets check we're on the same wavelength here.

First past the post means each electorate returns one member, being whoever got the most votes in that electorate.
Proportional representation means each (larger) electorate returns several members, being the several most-voted-for. Hence one could come third or so and still get a seat.

Preferential voting is where the elector marks all the boxes on the ballot paper with numbers beginning from one up to the end, and their vote is first given to the "1" candidate, but if in the first round of counting there is no candidate with more than 50% of the votes, the candidates with the fewest votes are eliminated and their votes are transferred to the "2" candidate, and the process repeats until someone gets over 50%.

Is this how you understand the terms?

It is possible to have combinations of both systems.
Down Under, we have preferential first-past-the-post for the lower house, and preferential proportional representation for the upper house (which is a little more complicated but I won't go into it).