Chapter headers smaller

[positronanton]

Hello, I am writing my thesis using your template. I am newbie with LyX and latex so apologies if this is a very basic question/issue. I am really grateful for you work, massive thanks, very useful.
I am transferring chapters that I wrote in Word during my PhD to LyX and so far so good. I like the way it looks when compiled and LyX seems easy for beginners like me. I am hoping to have the full thesis by end of the year in LyX which I might use to start learning Latex on the process.

Question:
I need to change the chapter headings to smaller size so I can fit an abstract for each chapter first page (journal style) which I did easily and it looks good when compiling a single chapters but when compiling full thesis the table of contents and the headings of the chapter carries that new format of the chapter title which does not look good at all.

how could I perform this change?
Kind regards
Jose