Minecraft's looks keeps glitching

Each time I exit a world then enter another or even the same one, the Terrain/looks glitch

What I expected to happen was to work normaly and for the terrain to load in.

What actually happened was all the blocks keep 'switching' around and i cant find anything

1.Open Minecraft
2.Go into a world or server
3.Exit the world or server
4.enter another world or server or, the same one.