It depends. If you edit elements, the personalizations remain intact. If you delete them, it might impact your personalizations.
Personalizations are like an additional layer of information that is sent to your website visitors. The difference between the personalized web page and the original one is described by a delta (or a diff). Every time you adjust content through Unless, a new delta is created.
When someone visits your website, Unless sends out the delta and replaces the original content. So technically, a personalization is just a group of content changes on top of your original page. It is not a separate, new page.
In general, changing the original page will not "break" your personalizations. In fact, updating texts or images will have no effect. However, if you delete elements your personalizations might not apply.
For example; if you remove a paragraph in the original page, the delta describing a change for that paragraph will not apply anymore. The paragraph is gone - there is nowhere to "dock" for the delta.
This only applies when you change the structure of your original web page, not the content. So, updating text or images will have no effect on your personalizations, however, deleting elements, will mean losing the personalizations within those deleted elements.