Editing a chart filter

Hello all,

I added a filter to one of my Top 10 charts the other day.  I'd like to go back and look at it for reference, my Edit button is gone.  Only the Help button is available.

First, is that normal behavior for the Edit button to disappear?  Second, where is the filter stored if I have to go edit it through some other interface - the database or in a flat file somewhere?

Thanks,

/jh