Change all pixels in one color to a different color

[Don298713684b0s]

I am new to Fresco. I started with a png file and made it a raster layer. I want to change a specific color everywhere to a different color.

[Imaginerie]

Generally changing a colour can be done two ways, if the shape is closed, you can fill it with the fill tool (the paint bucket shaped one) or you can apply a hue/saturation adjustment layer to another layer (by clipping it) or the entire stack of layers beneath it.
the fill tool

the adjustment layers

when using the Hue slider to change the colour (note the clipping curved arrow that points to the impacted layer there)

It would be best if you could show a screenshot of the whole window, so we can point out to specific tools and processes depending on what you are trying to achieve.

[Don29877882kgi4]

here is the image i want to change everwhere there is the specific red value (for example the area in the top right corner) to another color. It would be impossible/tediouse to select specific areas. Thanks for your help.

[Don29877882kgi4]

oops I meant left corner/side the large red area, there is also a small wavy one at the bottom center. I want to change that color everwhere

[Imaginerie]

It's not possible unless the different colours are on different layers (which would be a natural workflow anyway). If they are not, you can still use the fill tool, and play with the margin options as here:

The higher the margin, the more pixels it fills, do some tests to find the one that suits - you fill first, and then tweak the margin as you see the effect happening live.

and the additional options just like transparency (fills semi transparent shapes with semi transparent colour if enabled), and contiguous, which will only fill connected shapes (without any gap) if anabled. I think you'd definitely want this one enabled.

check the tutorial here:
https://helpx.adobe.com/fresco/using/colors.html
alternatively - although it may be a bit twitchy - you can use the magic wand to select based on colour AND shape, and use the fill brush, within that selection, to change only a selected area

https://helpx.adobe.com/fresco/using/magic-wand-tool.html

Hope it helps!