Conflict with theme?

I am using a theme that I purchased and have had problems since the beginning of my installation. I asked the person who made the theme for help, but he won’t answer my questions. After searching the forums for information, it seems there is a javascript or jquery issue.

I am very new to WordPress, so I don’t know how to find where the problem is. I did deactivate each plugin and checked the site to eliminate the possibility of a plugin causing the problems. The only time the plugins operate normally is when I deactivate my purchased theme and activate a different one.

As for problems, the most prominent ones include text fields and dropdown boxes in the admin/dashboard are really wide. Also, I can’t get any eCommerce/shopping cart, or invoicing plugins to function.

I really love this theme. I have already spent a lot of money on my website and would love to find a “fix” for the problem rather than spending a lot of time trying to find another “perfect” theme.

The site is https://kustombykris.com