Composer installs Extensions to /vendor but Magento path is /app/code Fails to Load

I installed a magento extension via composer require

I can see the files in /vendor but when I click on the extension from the admin panel it gives me an Exception that the Class does not exist as the link to the extension is set to /app/code. If I copy the /vendor folder to /app/code it works but then I get errors if I use php bin/magento setup:upgrade about the extension already being defined in vendor

There must be a path set somewhere telling magento to look for extensions in /app where I do have some webkul extensions installed.

What should I do?