OPP is telling drivers to remember the following rules when using roundabouts:
When entering a roundabout:
Visual checks: Do visual checks of all vehicles already in the roundabout and those waiting to enter (including cyclists).
Look left: Traffic in the roundabout has the right-of-way. When preparing to enter the roundabout, pay special attention to the vehicles to your left. Adjust your speed or stop at the yield sign if necessary.
Adequate gap: Watch for a safe opportunity to enter the roundabout. Enter when there is an adequate gap in the circulating traffic flow. Don't enter directly beside another already in the roundabout, as that may be exiting at the next exit.
Travel counterclockwise: Once in the roundabout, always keep to the right of the central island and travel in a counterclockwise direction.
Keep moving: Once you are in the roundabout, do not stop except to avoid a collision; you have the right-of-way over entering traffic. Do not change lanes while in the roundabout. If in the inside lane and you miss your exit, you must continue around until you meet your exit again.
When exiting a roundabout:
Signal: Be sure to signal your exit and watch for pedestrians.
Maintain your lane: Stay to the left if you entered from the left lane or stay to the right if you entered from the right lane.
Maintain your position: Maintain your position relative to other vehicles.
Signal intent to exit: Once you have passed the exit before the one you want, use your right-turn signal.
Left lane exit: If exiting from the left lane, watch out for vehicles on the right that continue to circulate around the roundabout.
That's not really how roundabouts work. In 2 lane roundabouts the outside lanes have mandatory exits where the inside lane can exit as well (since the outside lane cannot continue, there is no accident risk). In some roundabouts the inside lane becomes the outside lane at these junctures. At others the incoming outside lane takes over as the outside lane.
In any case, when entering a roundabout there is signage which tell you which lane can do what, so you only have to enter the roundabout in a lane that goes where you want.
This is no different than any other intersection, you have to be in a lane that goes where you want and you shouldn't change lanes in an intersection. It's illegal in many provinces and counterindicated in others.
https://www.theglobeandmail.com/drive/mobility/article-is-it-illegal-to-change-lanes-in-the-middle-of-an-intersection/