Each time you re-visit a website, your cache (temporary internet files) is supposed to  to analyze if it has changed so that it can serve you the most up-to-date pages. This doesn't always work; sometimes the cache will load its older stored page instead, so you may not always get the newest version.

In Safari

1. Open Settings
2. Swipe down and tap Safari
3. Swipe down again and tap Clear History and Website Data, tap it once again to confirm

Alternately, if you’d like to clear data from individual websites without clearing the entire Safari cache, at the very bottom of Safari settings choose Advanced > Website Data > Edit (or swipe from right to left to delete individual items).

Keep in mind website data deleted from iPhone or iPad will be removed from your other Apple devices signed in to the same iCloud account if they sync with Safari.

In Chrome 

1. On your iPhone or iPad, open the Chrome app .
2. At the top-right, tap More .
3. Tap History  Clear browsing data.
4. Make sure that there’s a tick mark next to 'Cookies, site data' and 'Cached images and files'.
5. Tap Clear browsing data.

 In Firefox

1. Tap the menu button at the bottom of the screen (the menu will be at the top right if you're using an iPad):
   

2. Tap Settings in the menu panel.
3. Under the Privacy section, tap Data Management.
4. Tap Website Data.
5. Tap the red button next to each site you want to clear, tap Delete.