If you would like to change some texts from english to english (translating to another language is described here) you can do it using SayWhat? plugin that allows you to alter strings on your site without editing WordPress core:
After installing SayWhat? plugin go to Tools → Text Changes and click “Add New“. In “Original string” field write original text, then in “Text domain” field add realteo or findeo and in “Replacement string” field add new text.
Some texts might come from theme and then the textdomain is findeo or from plugin then it’s realteo