If anyone's scratching their head like me in 2025 version of IDEA, they've moved it to Settings -> Advanced Settings -> Version Control -> Use modal commit interface for Git and Mercurial. And the whole thing is a separate plugin now, not sure why they consider this a feature, rather than removal of it... Context -> https://youtrack.jetbrains.com/issue/IJPL-177161/Modal-commit-moved-to-a-separate-plugin-in-2025.1-Discussion