I use Lyx version of classicthesis: classicthesis-LyX-v4.2_biblatex_bibtex8.
Since I have long chapter and section titles, the Chapter and section headers go off page, as shown below.
I want to remove the titles and change them into Chapter i, Section j respectively. If this is not possible, then I want to have short titles instead of full titles.
I have not found any solutions for Lyx version (maybe just because I could not understand the solution for Latex version).Please provide step-by-step beginner-friendly solution.