New template, settings not sticking?

I’m trying to create a new template and am having mixed success. I want to get the compile to default to plain text with double spacing. The documents are sticking, as is the default compile type and “convert to” settings , but the settings that are in the editor (e.g. line spacing) are not.

Can anyone suggest how I can get the output to double space in plain text?

If I understand you correctly, this isn’t something you would be doing in the Formatting pane. There is no such thing as formatting a plain-text file. Manipulating plain-text into a double-spaced document would require text alternation; specifically hard-wrapping the text at a determined column (and potentially indenting paragraphs with spaces), then doubling the newlines to space things out. Post-processing the compiled file in something like TextWrangler would be your best bet.