Is there a way to search for a string in files that have changed? I want to search for the comments I've added before I commit them, but I only know how to search for comments in every file of my project.
Searching changed files is an option in the "Find in Files" functionality:
By default, IntelliJ searches your entire project, click the button "Scope" to choose a specific search scope, choose one of the "Local changes" variants. Don't miss that you should scroll down to see these options, the scrollbar might be displayed as hidden.