As a way forward, I highly recommend working from a “child”/derived theme rather than editing your copy of Quark. This protects you from losing your work when you upgrade the theme. Read about theme inheritance in the docs.
Also there are quite a few cache settings in Grav which work in addition to the ones in your browser and on your web server. These are mainly described in the system configuration section. I disable cache on everything but production (live site) servers.