The release is available from the download page:
http://www.high-logic.com/download.html
Just install the newer version over the top of the older version. You don't need to uninstall the older version first. This method ensures that any options you have set are retained.
Fonts created with version 4.5.0 through "File --> New -> Unicode" should be fixed by following these steps:
- Open the font in the Font Creator Program.
Go to Format --> Settings --> Ranges tab --> Code Page Ranges and press the Edit button
Scroll down and uncheck "Symbol Character Set"