64 bit compatibility

Every time I open up Arduino on my Mac, I get this error code: "App is not optimized for you Mac and needs to be updated."Apple is transitioning to 64 bit and this is a 32 bit application. How would I update? Do I need to update?

Arduino is aware of this issue, last I saw they were hoping to have a new fully 64-bit version before the non-beta release of whatever the version of mac OS that enforces this comes out.

I think progress is going well on this issue. There is a beta test version already available that can be downloaded here:

Do I need to update?

No. This is only an issue for the people who are beta testing macOS 10.15 Catalina. There is no problem at all for people who are using previous versions of macOS. It's just a warning intended to prompt developers to get ready for the change, and Arduino is already doing that.