Full-screen display in Responsive view does not work automatically on smartphone

Hello, we have purchased the Catch Evolution Pro 3. 5. 4 theme from you and are using it. We have a problem with this theme. On the smartphone, the page is displayed responsively, but not full screen. To display the entire page, you must first zoom in. When switching to a submenu, the full screen zoom is lost again. We tried an older version of the theme (3. 4. 2). Everything works perfectly there. Deactivating plugins was not successful. Wordpress version change from 5. 2. 2 to 5. 0. 4 was also unsuccessful. Only version 3. 4. 2 of the theme works fine. Do you have a suggestion on how to do this with Theme 3. 5. 4? Thank you very much. Many greetings Manfred