@Vert-Liberte
When you change the color scale, the same modification will be applied to all your devices.
Go to Settings
Scroll down and choose Customize color scale
Select overlay:
Rain accumulation
At bottom of page find the line Import/export
Click on [view code] to open a window pop up
Delete the text code in this window
Select and copy all lines of code here below and paste them in the window
Press [Import Gradient]
Press Save
You can come back to the default Windy settings at any time by pressing Load defaults

[[0,[130,130,130]],
[1,[131,129,142]],
[5,[97,88,132,255]],
[10,[52,117,142,255]],
[30,[11,140,136,256]],
[40,[53,159,53]],
[80,[167,157,81]],
[120,[159,127,58]],
[250,[190,76,7]],
[500,[207,40,71]],
[750,[175,80,136,256]],
[1000,[212,118,163,256]],
[1500,[250,157,190]],
[2000,[220,220,220,255]]]

Updated Summer 2023

A90EF84A-8984-4955-BE13-39794FEA9BB4.jpeg

If you want to use other colors, see
https://community.windy.com/topic/10336/customize-the-color-scales-of-windy-layers?_=1698745406888