Updating main CSS file does not actually show changes on the websites. help

Hello,

I have (I think) unlikely problem. I am trying to make some changes to main styles file (I am trying to edit .site-title header in style.css) but the changes are not actually working. I make changes (even like changing the color of the site title wording), I “update”the style.css file and the changes do not work (even though the parameters I changed have been saved).

Please help as I basically cannot edit anything in the style.css

Thank you