Problems with VC upgrade - advice please

Wordpress version 4.8 - have just updated the Visual Composer plug-in, by uninstalling the old version and installing the new version in accordance with the instructions.

When it comes to editing the website I can make changes from the website view (Front End editor) but I prefer to use the Backend Editor - in the Backend Editor for pages I choose Edit with Visual Composer - visual composer does not kick in and I’m left with conventional classic editing…

Please can you offer advice asap.

Thank you