Flash is a program that runs applications and animations among other things. Many programs (including websites) when first open take a super small amount of storage. Sometimes these writes can cause problems which can cause the problems of things not showing up on websites or even applications. What you are doing in clearing what is stored and when you then go back to it again it will then but it back into cache for further usage. You don't loose anything important Flash will get what it needs again once you clear the cache.
Flash can be in one of two areas: on your computer itself. With your search, start typing in flash and it should pull it up (Flash Player control panel) . Under the 'storage' section there will be a 'delete all' button, click it...done. If you are using Chrome it will say near the bottom of the page (on the control panel on your computer) about if you are using Chrome to follow a link. Do so, go to the 'web privacy setting' section (should be the 5th icon within the box on the right), click 'delete all sites.' With this being done, you might see slower load times when you first reload webpages.