Open the FBP options screem by clicking the "FBP" button in the navigation bar at the top of the page.
Under the "Further options" heading there is a setting titled "News Sort: Most Recent". Tick that option, then click the "Save and Close" button.
As mentioned above this is not guaranteed to fix hiding the sponsored posts, but a lot of people are reporting success with it, as Facebook seem to pepper the "Top Posts" version of the Newsfeed with more ads than the "Most Recent" version, and "Top Posts" is Facebook's default setting for the Newsfeed.
You can use the safe, free and top rated FB Purity browser add-on to get Facebook back to how it used to be (without ads,memes, images, videos, game posts, etc etc : http://fbpurity.com
Under the "Further options" heading there is a setting titled "News Sort: Most Recent". Tick that option, then click the "Save and Close" button.
As mentioned above this is not guaranteed to fix hiding the sponsored posts, but a lot of people are reporting success with it, as Facebook seem to pepper the "Top Posts" version of the Newsfeed with more ads than the "Most Recent" version, and "Top Posts" is Facebook's default setting for the Newsfeed.