Hello. My name is***** can help you with your question.
People have experienced various compatibility issues after upgrading. But, the issues do not appear to be with the operating system itself, but rather with the upgrade procedure not necessarily upgrading the software correctly. If you're having compatibility issues, you can uninstall and reinstall the software, but it is very important that before you uninstall it you deactivate it. Otherwise, it will not activate after the installation. If you deactivate it, uninstall it, restart your system and then install it again from scratch and activate it, it should alleviate any problems that you have with Yosemite that you did not have with the previous version of your operating system. Let me know how you make out and we can go from there. I will help you until your question is fully answered.