Editing on part of cursor and then changes are made in other sections

Hi guys,

Whenever I feel like I am making progress on a specific are I then find changes are made that I had previously made and then I feel like I am chasing my tail fixing bugs.

I don’t have cursor rules set in as not sure what to make as rules. Could this be the issue? Is there any advice on this? Is anyone else experiencing this?

I am looking into setting cursor rules however I am not too sure what to select as rules.

Thanks