Form width

The change in the width of your contact form 7 after updating it is most likely due to CSS rules which were applied directly to Contact Form 7 or the theme without using a child theme or a custom CSS plugin.

To change the width of your CF7 forms you would need to edit the CSS style sheets used by your WordPress theme.

See Styling Contact Form for a general explanation of styling CF7 forms using CSS.

There is a link at the bottom of the page to a comprehensive and detailed article on Styling Contact Form 7 Forms.

Use Firebug or Chrome Dev Tools to to examine the HTML and CSS of your CF7 form in detail. Once you understand how the HTML and CSS is configured in your CF7 form, you should be able to see the CSS changes you need to change the appearance of the form to suit your requirements.

It is important to add your CSS via Child Theme or use custom CSS plugin.

Thats what i tried;) I try to edit the form into the CSS file but without any result, were it works on other projects, it wont on this one:(

Use Firebug or Chrome Dev Tools to examine the HTML and CSS of your CF7 form in detail. Once you understand how the HTML and CSS is configured in your CF7 form, you should be able to see the CSS changes you need to change the appearance of the form to suit your requirements.

You can learn about these extremely useful developer tools at the following links:
https://getfirebug.com/wiki/
https://www.evotech.net/blog/2007/06/introduction-to-firebug/
https://www.youtube.com/watch?v=sHbYpl1XFiM
https://www.tipsandtricks-hq.com/debugging-javascript-code-with-firebug-1899
https://developers.google.com/chrome-developer-tools/