You need to always check two things:

1. That your current template is the one you're testing. If you have more than one template installed, you can choose the default one in the Studio> Designer settings. Also, ensure that as a user you have selected your current template - there's a link in the site footer called "Template". Once you've settled on one template, we recommend deactivating all other templates and this won't be an issue.  

2. Cache. Templates changes are all saved in CSS, which is heavily cached by browsers AND on-server by UNA to improve loading speed. Go to Studio > Settings > Cache and disable cache for CSS while you're working on styling, and also make sure to clear browser cache when reloading your frontend to see changes. To avoid getting logged out every time it is best to make changes in one browser (say, Firefox or Safari) and test them in another (say, Chrome, where you can clear cache easily).