Try pressing CTRL+R on your keyboard. This refreshes the page and clears anything your browser has stored in its cache, forcing it to load a brand new version.
We are constantly making updates and improvements to our product, and more significant changes require your browser to be reloaded to take effect. In most cases, your browser picks up these changes automatically — such as updates made to an asset. Occasionally, though, it doesn't realize something has changed and gets stuck displaying an older version. CTRL+R (short for "Reload") is the easiest way to get it back on track.