@Wampa, I have a KitchenAid electric double wall oven with similar features. Mine have convection and traditional Bake and Broil and convection Roast (no traditional Roast as you have).
Per my manual and my particular ovens, the difference between Convection Bake and Convection Roast is the use of the upper heating element during cook time with the Roast setting but NOT with the Bake setting so you should choose based on whether you want heat from that upper element or not. In general, you can use Bake with trays of cookies or cakes on multiple racks in the oven but when you're using Roast, you want to stick with one rack, usually in the middle of the oven. If you use Roast with multiple racks, the stuff closer to the broil element is going to get a lot more heat and even rotating them isn't going to give you the most even bake.
On convection bake, during preheat, the lower heating element (under the oven floor), the broil element and the rear element (behind the back wall of the oven, near the fan) all operate but once it's heated up, only the lower element and the rear fan element cycle to maintain temp during cook time. No broiler element during convection baking.
On convection roast, all three elements (lower, broil and rear fan elements) operate during preheat and all three cycle to maintain temp during the cooking time. So there will be heat from the broiler element during convection roasting.
I always use a convection setting during preheat as it will get to temp a lot faster and I use convection for most things. If I'm worried about a baked item drying out due to the fan, I switch to traditional bake after it's up to temp.
My ovens do not automatically reduce the temperatures when choosing Convection as @TdeV's does, though there is a "convection conversion" feature called "Easy Convect" on my ovens that's available to do that. I have never used it.
I do always monitor the temp inside the oven with a digital thermometer probe (Thermoworks Dot or Square Dot).
Oddly, when using convection, the temp probe in the oven always reads about 25 °F HIGHER than the temp set and displayed on the oven panel so I do usually set the temp 25°F lower when using convection and check for doneness earlier. I don't see that increased oven probe temp on traditional bake.
In my oven, on traditional Bake, it will be hottest at the rear, opposite the door. On convection Bake, it will be hottest near the door, opposite the fan. Either way, I rotate pans of cookies, etc. for even baking whether I'm using convection or not.
Check your manual to see if this matches and monitor the temps in the oven with a good thermometer.
