As to how to tell which axis is which, there are lots of ways. You can tell be the direction in which the curve is travelling, you can tell by the coloring of the curves (in the order blue, orange, green), you could use plot labels to labels the axes etc.
Just make a couple of plots and see what the default colors are for the first, second, and third plot. Then see where those colors end up in your 3D plot.
Or otherwise, just look what the curves look like. One is a sin curve, the other one is a cosine. Like I said, lots of ways.
@anhnha Of course you do, if you plot ParametricPlot3D[{f1, f2, f3}, ...] then you know that f1 will be colored blue, f2 will be colored orange, and f3 will be colored green. But if you don't like that, why don't you add labels like I suggested?
I consider this a bug in the front end. Very odd it is, that not all forms eat up the first result. Consider this simple example
m = {1};
MatrixForm@m
MatrixForm@m
which gives 2 outputs as expected. If we look on the traffic between kernel and front end, then we see, that the kernel indeed sen...