I’ve opened an existing document. I can change between double and single space, but the single space still has too much spacing. How do I change how “thick” the spacing between lines are?
NOTE: This changes the spacing between lines in a paragraph, but not between paragraphs. When you hit the Enter key to insert a line break, it forms a new paragraph. If you see that adjusting the line spacing is having no effect, insert a line break by holding down Shift while you press Enter to insert a line break instead of a paragraph break, and your line spacing should work as expected.
There are several options in the paragraph style, besides single and double line.
please see also https://wiki.documentfoundation.org/Documentation/Publications#LibreOffice_Writer_Guide
Chapter 7 Working with Styles page 9
How can i set this configuration for all new document automatically, are there any global option.
or look in documentation about templates.
Use proportional line spacing under Format / Paragraph and a percentage less than 100%, as shown in the example:
which uses the following paragraph format for the right-column paragraphs:
This was using LibreOffice 3.5.7.2.