How do I use an editor to format my modules without losing all the styling from the quickstart.
It depends, but I will try to help you:
1) In Joomla all module in back-end can have "note" field where you can write warning for you "Do not edit with TinyMCE"
2) But in general it's because of HTML5 tags. But for example JCE allows you to use different settings:
https://www.gavick.com/documentation/un ... d-editors/