How to make my "Time Capsule" drive not viewable by everyone on my wifi network?

how can I change the settings such that no one (including even me) can connect to the Time Capsule over wifi without a password?

Change the shared disk password.

You probably have the same wifi password used for everything on the Time Capsule now. This is due to the way the setup wizard guides you through the setup but it is easy to fix the problem. In the Airport Utility click the icon of the TC, click edit in the summary.. then go to the disk tab and change the security setting for shared disks.

Use disk password. Type in a new password for disk access.

You should also change the access password for admin.. but that is up to you.

how else can I make the Time Capsule inaccessible/invisible to guests logged in to my home wifi network?

This is easy.. do not give them access to your main wifi.. setup guest wifi access. I am assuming your TC is the wifi router in your network. If not then it will depend on what model main router and wifi access system you have. We will need more info to help.

Go to the wireless tab and enable guest wireless .. with or without a password is up to you.

Do not hand out your main wifi password. Guest wifi allows internet access but no local network discovery or access.