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When you change the tempo of your project in Logic Pro X it automatically changes any midi in your project to fit the new bpm. However, audio files by default will not change. However, you can make them change to follow the tempo changes, and in fact all you need to do is check a box for each audio track you want to follow the bpm!
Just Turn Flex & Follow On
tldr; Just check the "Flex & Follow" checkbox in the inspector of the audio track whose regions you want to follow the bpm when you change it.
If you want to learn more about the flex and follow options, this is a great post about it in the Logic Pro docs.
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