Hi,
So I assume you using Portal engine and making changes on the Design tab of a page?
Any change you make to Widgets (Page tab) or fields (Forms tab) are tied to that specific culture version of the page.
Any change you make to Web Parts (Design tab) or template (Master Page tab or in templates application) will be done directly to the template and reflected on EVERY page using that template!
If you need to make changes to a Web Part for a specific (set of) page you either need to create a new template or make that Web Part into a Widget.