How Can I Force Pages To Refresh After Theme Change?

I'm relatively new to Wordpress and everything's gone very smoothly, except theme changes. If I've already viewed a page and I decide to change the theme, I cannot get the page to reload with the new theme.

Environment: Wordpress Multisite on Hostgator Business Shared Plan, using Parked Domains.

What HASN'T Worked: Clearing WP Cache (all), Clearing Browser History (all), Switching Browsers. I assume the problem is caching either at the WP or HostGator level.

Can anyone tell me how to clear the cache and/or force the pages to reload with the new theme?