Website page not updating in certain browsers – old content showing

My problem is that my site – androidwikihow.com is not showing updates in certain browsers unless I forcefully clear the browser’s cache.

The problem is started from five days ago.

I use the SiteGround SuperCahce plugin, Gzip compression and leverage browser caching. My Hosting provider SiteGround told me that all is fine from their side.

I don’t understand what to do now..

Does anyone know what may be causing this? Please help me