Am I making the change in the wrong place? how do I decrease this excessive boarding/deboarding time?
It's not clear from your message if you have GSX Level 2 enabled, so you are referring to the supposedly excessive boarding/deboarding time of animated passengers. If you have it, Page 26 of the manual contained the explanation and the solution:
When the GSX Level 2 Expansion is Active, the Deboarding/Boarding settings in the Timings page will look different. Since passengers are now no longer simulated, but will appear as actual animated characters, the original timings in seconds/passenger will not be meaningful anymore: the time required to board passengers will be a combination of their walking speed and their density. Each passenger has its own walking speed, which depends by its
animation and walking style, but it’s possible to control the passenger Density, which will affect the number of animated passengers visible on screen at any given time.
Setting the slider towards the highest density settings will shorten boarding and deboarding times, but with some cost in performances.
The parameters in the Couatladdons.ini file will only used when there are no passengers, for example on a parking spot with the Bus disabled, or on a gate that doesn't have SODE jetways.