Just want to know if there's a way to change the default sorting method for all deck lists.

I see it's by Name now, but I swear it used to be by Cost. I'd like to set it back to Cost if possible, thanks!

I might be wrong (and I don't know how long ago you mean) but I've been using the site for ~3 years and in that time I think it's always defaulted to sort by name.

I do agree that having a checkbox or setting to choose your default sort column would be a nice feature though.