How do i change the default location certain files are downloaded to?

For example when i ';save picture as'; how do i make it go to my external hardrive without having to browse?How do i change the default location certain files are downloaded to?
When you save your first file or picture, change the directory then to wherever you want it saved as. Rest of the files you save will automatically go to that location from then on unless you change it.How do i change the default location certain files are downloaded to?
go into the settings / tools or options of the program that you use.