First post here, so thats going for me 
I’ve been using TR for about 6 months now and I’m very satisfied.
Now to the request and maybe it’s been discussed earlier, but I would love the ability to see my Training Stress over longer periods. A setting that change the period from a week to say 9 or 11 days.
Or maybe a rolling 9-day period?
Sounds like you’re referring to a CTL, ATL, and TSB metric. Currently, TR doesn’t offer that. You’ll need to use TrainingPeaks or Intervals.icu.
Actually I just want to, at the Training Stress page, see the load of my training over 9 days instead of a week.
I’m not aware of any program that has 9+ day load (TSS) totals. The cycling world bases load on a weekly basis.
You can set different time periods for your ATL/CTL (sort of …) in Golden Cheetah. In the Model-page in Athlete settings they are called STS and LTS but it is basically the same.
There is an extensive thread at intervals.icu on how to calculate ATL and CTL if you wan’t to calculate it yourself.
I’m not aware of a way to change it’s default 7 day time frame in TrainerRoad.
A personalized time period could make sense if you recover slower or faster than average.
Edit: Added a link to an on ATL etc. article by Jonathan.