IntelliJ IDEA: how to revoke reformat code / optimize imports dialog?

Question

So I've pressed Do not show this dialog in the future (screenshot taken from the web).

It's been a while and now I want to change default reformat behavior.

I can't seem to find an option to show this dialog again.

Answer 1

Update 2015/10:

In current versions of IntelliJ (and likely Android studio and other IntelliJ based IDEs) there no longer seems to be this option as it is not needed.

⌘+Alt+L no longer shows the dialog, instead it directly reformats the file and gives you a hint that you can display the dialog using ⌘+Alt+Shift+L. That dialog no longer includes Do not show again option.

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For older IntelliJ versions these dialogs can be re-enabled in Settings/Editor/General: