To find your previous posts, there's a few ways. eg: click on your username & choose Find all posts. Else, click on the User CP (control panel) button top left & then click on the link on the side to show all threads you're subscribed to.

I just had a look at your other posts & there are no other responses.

1. Which Mac OS version are you running?
2. What type of files are you trying to open?
3. What are the default programs for opening your video or audio files?