To answer you question I had to break the answer to 3 Parts:
Part #1: How to bulk change Font / Font Weight:
- Open Menu
Type > Find Font >

This will open a dialogue box with all your used fonts listed.
- Then you can change all your fonts Or font weights assuming you're using multiple fonts and you want them all changed By Clicking on each font then choose your final font from
Replace With:
Panel.
This Dialogue Box also gives you control on missing fonts in any document in case you have any. But unfortunately this dialogue cannot control text color.
Part #2: How to bulk change text color?
I Couldn't think of any tool I can use other than using scripting.
Open Menu Window > Utilities > Scripts
Or Press Ctrl+Alt+F11 to open the scripts panel menu.
Right Click on "User" > Reveal in explorer
.
In the opened location Create new JavaScript document and name it as you want, then Save it.
Paste the following script to the newly created JaveScript document...
main();
function main(){
var myDocument = app.documents.item(0);
var myTextFrames = myDocument.textFrames;
//Create a color.
try{
myColorA = myDocument.colors.item("Yellow"); #Change the name of the color as you want
//If the color does not exist, trying to get its name will generate an error.
myName = myColorA.name;
}
catch (myError){
//The color style did not exist, so create it.
myColorA = myDocument.colors.add({name:"Yellow", model:ColorModel.process, colorValue:[0, 0, 100, 0]}); #Change the name of the color as you want and change the combination
}
//The following for loop will fail to format all of the paragraphs.
for(var i = 0; i < myTextFrames.length; i++){
var myText = myTextFrames.item(i);
var myTextInside = myText.parentStory.paragraphs;
for(var j = 0; j < myTextInside.length; j++){
myTextInside.item(j).fillColor = myColorA;
}
}
}
Change the name of the color as you want and change the combination, Then Save it
I've indicated the places you should change in the code by "#" mark.
Return to inDesign, You should see the newly created script name in the menu.
Right Click on the Script > Run script
the script should run and change color of all of your text in the document your selected color.
Part #3: How to bulk change font size?
You didn't mention it, But I assumed that you may want to do it also, Who knows?
Add the following line to the previous code
myTextInside.item(j).pointSize = 9; #choose you selected font size
Right after myTextInside.item(j).fillColor = myColorA;
. And inside the closing curly bracket }
.
- Save the script.
Right click on the script name > Run script
and the script will change all text to selected font size.
Actually this script can be modified for further customization. Scripting for inDesign or any Adobe software is incredibly powerful and can make almost every thing automatically. You may refer to this link for more Adobe inDesign Scripting official documentation.
Next time try using Paragraph and Character Styles it's very powerful feature and gives you a lot of controls for text and fonts.