How can I change to a color on our house it is dark cedar

https://www.thespruce.com/painting-cedar-siding-guide-4125927

You'll have to keep repeating this process because it is the nature of the wood to darken. How to Lighten Cedar Siding | This Old House

How about changing the trim and paint the metal around the windows instead?

This site gives you several options for articles. Hope it helped.

https://www.google.com/search?rlz=1C1BLWB_enUS700US700&ei=w2cMWquoDNbEjwODz7uQCg&q=staining+a+darker+cedar+siding+wood+lighter&oq=staining+a+darker+cedar+siding+wood+lighter&gs_l=psy-ab.3...7456.22176.0.22606.27.18.9.0.0.0.155.1370.14j3.17.0....0...1.1.64.psy-ab..1.0.0....0.6b4WP0806hU

You could use a "white wash" by mixing 1 part paint with 3 parts water (add more water for less "color") test on a small area. brush or roll on and wipe off excess until it looks how you want. A gray-ish tint would give the cedar an aged patina and a sage green or turquoise wash a copper look. Remember that areas that get a lot of sun will be more porous and will absorb more paint... you may need to apply a wood conditioner before painting to get even coverage.

A brighter window trim color would really change the look too

Before taking on the huge job of bleaching all the siding, I agree with the other posters - try a lighter color on the trim. I'm picturing a light, neutral tan or a warm stone grey.

I'm thinking Sherwin Williams Butter Up yellow for a new trim & window color. Once the siding has been lightened up & sealed, I think you'll enjoy the new trim color. Best of luck with your project.

Lightening the house will make it look less expensive. Maybe change the landscaping to something elegant and very manicured - it will brighten up the house. Deep greens with pops of yellow/red or blue/purple.