Version 3.5 upgrade

What is the correct proceedure for upgrading from 3.0 to 3.5. I replaced all files in the codebase folder but it appears nothing has changed. For example my time line bars do not have a start and end drag function. Does the feature need to be changed in configuration before it will work.

Also I now can not edit recurring events on my booking system. Attempt to edit the recurring event gives javascript error dhtmlx.modalbox is not a function in dhtmlxscheduler_recurring.js.

It seems like I have missed something during the upgrade process.

be sure that old js files not cached
you can replace existing

with

it will prevent old version caching