I would like to use the citation style: author, year. Which configuration do I have to use? If I do \usepackage[comma]{natbib} it collides with the preferences where I can only chose between numerical and author-year. It does not need to be natbib, I even prefer the Standard plain style, but simply would have author,year instead of [1].
Would be thankful for any help.
Nothing bibliography related has to be written to the preamble. Select natbib/plainnat and author-year in Documents -> Settings -> Bibliography. Then, right-click on inserted references and select desired citation style.