I'm using my default calendar too, but I have no problems with it and it synch's automatically with my Google account. I have the HTC Droid Incredible. If I want to edit something, I just pull it up, press the menu button and select Edit. Or even easier, go online on my computer and edit it there.
I noticed on my adroid tablet an app called HUBkap mobile, this has a calendar app built-in too and maybe you're using this? If you are, I don't know anything about this app, I deleted it from my tab.