This is more about optics.
I’m using MBED Studio on Linux Ubuntu 18.04.
Steps to follow.
Right click on folder of choice and select “Find in Folder”
Enter a search term… in my example I entered “List”
It will then return you with a list of files with those search terms.
Click on a file of choice to open.
Now on left hand side click on icon “Clear Search Results”.
This clears the search terms on the left but I am still left with all my old search results highlighted in the file.
You have to close the file and reopen file (or close/reopen mbed studio) to clear the result on the file itself.