First of all, thanks for reaching out.
To successfully change the dimensions of your widget, please ensure that you click Save at the bottom of your screen. These changes will reflect in your website(after you paste the code). Any other changes you make after that doesn't require you to copy & paste the code again, as long as those changes are saved.
To see other styling options, you can use Chat surveys to access two other modes besides Inline Embed(Pop-up Card & Chat). With these modes, you'll be able to access other options to customize & style your widget the way you prefer.
For more information, please refer to this article37.
Hope this was helpful! :)