Apple maps changing route by itself

Hello!

How do I stop the maps from changing the route from my original selected one? I drive bulk trucks for work and often have to choose a specific route due to curvy mountain roads, inability to perform uturns, tight residential streets, etc. But maps constantly change it to the “fastest” or “best” route in it’s opinion. Which creates a hazard really because you have to adjust it while driving at that point.

I also like to explore countryside on backroads and try to take a different road each time I travel, this feature is super frustrating!

I use different gen iphones for work and personal life. This has been happening to me across all devices, several ios updates. So it’s not that.

Someone, please, help. It’s driving me up the wall.