Why would you ever want to double space words rather than lines? If that's
a publisher's request, they mean lines and not words. But if you do, you
could do a global search and replace of one space by two.
do the document as normal, then when done,go to the edit menu, then select
replace. in the relace box, put in a space, and in the replace with, insert a
double space. the select replace all.