Why is my website loading an old version even after clearing cache?

I have updated my website but I'm having trouble with viewing the update. When I type in the website url without a directory, the website is loading an old version. To see the new version I have to clear the cache on only that website or type in a directory. If i clear the browser cache, it goes back to only seeing the old version. Is there a way in php or htaccess to fix this problem?