IntelliJ
How can I start over if I’ve messed up my IntelliJ setup?
See the how-to video ‘Start over your IntelliJ setup’.
How can I turn on distraction-free mode in IntelliJ?
See this Stack overflow article.
Why do I get an error message Class JavaLaunchHelper is implemented in both /Library/Java/JavaVirtualMachi...
?
This is a known bug in the current version of IntelliJ. For now you can safely ignore it.