How to do colorsplash in a gif
A tutorial on how to do colorsplash on a gif + change a color to another color
After you have loaded your gif into Photoshop and are ready to colorsplash it..
If it's too dark, just brighten it up however you like. I don't put any PSD's on it cuz I don't want it to mess with any original coloring.
So I went from this

To this

All I used was a Curves and a Levels layer (Layer > New Adjustment Layer)
You can make it as bright as you wish
After you're done with brightening
Go to Layer > New Adjustment Layer again and select Hue/Saturation
Now click the dropdown menu where it says master

Go into each color category and turn the Saturation all the way down to -100

Note: Do this for every color EXCEPT the color you want to stand out (and don't mess with Master either).
(i.e. I'm making the blue stand out so I do not mess with Blues/Cyans)
You don't have to do this but here I'm making my Blues/Cyans to be +45 in Saturation
This is optional, but if you want to do it you can adjust your Saturation to be however you want it (I just put mine at 45 cuz that looked good for this gif)

This is the result

OKAY NEXT
How to make one color to be a different color, like this..

So basically you do all the steps I said above ^^
The only thing is when you get your Hue/Saturation layer, leave them all at 0 (i.e. DO NOT make them -100, I mean unless that's how you want it, but I'm not doing that for this)
In your Hue/Saturation Layer
I went in the Blues/Cyans and made them -180, but you can play around and make it whatever color

Basically that's all I did.
After you have loaded your gif into Photoshop and are ready to colorsplash it..
If it's too dark, just brighten it up however you like. I don't put any PSD's on it cuz I don't want it to mess with any original coloring.
So I went from this

To this

All I used was a Curves and a Levels layer (Layer > New Adjustment Layer)
You can make it as bright as you wish
After you're done with brightening
Go to Layer > New Adjustment Layer again and select Hue/Saturation
Now click the dropdown menu where it says master

Go into each color category and turn the Saturation all the way down to -100

Note: Do this for every color EXCEPT the color you want to stand out (and don't mess with Master either).
(i.e. I'm making the blue stand out so I do not mess with Blues/Cyans)
You don't have to do this but here I'm making my Blues/Cyans to be +45 in Saturation
This is optional, but if you want to do it you can adjust your Saturation to be however you want it (I just put mine at 45 cuz that looked good for this gif)

This is the result

OKAY NEXT
How to make one color to be a different color, like this..

So basically you do all the steps I said above ^^
The only thing is when you get your Hue/Saturation layer, leave them all at 0 (i.e. DO NOT make them -100, I mean unless that's how you want it, but I'm not doing that for this)
In your Hue/Saturation Layer
I went in the Blues/Cyans and made them -180, but you can play around and make it whatever color

Basically that's all I did.