Hi Ian,
Welcome to The Forum and a Happy Christmas to you!
Another way to achieve this is hover the mouse pointer over the Icon of the curve you want; it will change to a curved arrow. If you are on the left side of the icon the arrow points left and to the right if you are on the right side. If you already have a piece or track laid, you should see a "wire" version appear on the join of that piece when you hovering.
It's easier to do than explain but once you get the hang of it it is quick and easy. Gordon's advice above is great if you need to correct a piece. If you do need to reverse a piece do not do it in the middle of a completed section as the track can jump all over the place. In this instance it is best to move one piece of track next to the one that needs reversing and when you have done reversing simply slot it back in place.
All the best - Greg
Welcome to The Forum and a Happy Christmas to you!

Another way to achieve this is hover the mouse pointer over the Icon of the curve you want; it will change to a curved arrow. If you are on the left side of the icon the arrow points left and to the right if you are on the right side. If you already have a piece or track laid, you should see a "wire" version appear on the join of that piece when you hovering.
It's easier to do than explain but once you get the hang of it it is quick and easy. Gordon's advice above is great if you need to correct a piece. If you do need to reverse a piece do not do it in the middle of a completed section as the track can jump all over the place. In this instance it is best to move one piece of track next to the one that needs reversing and when you have done reversing simply slot it back in place.
All the best - Greg