I keep getting plain worlds on Minecraft pc?

So I play the Minecraft app on my phone but I keep making worlds with random seeds, and every world they give me only have 1 biome: just trees and grass. There aren't any snow biome, no savanah biome, no roof forest biome, no mushroom biome, just a world full of trees and grass and sometimes a lake. I barely get any villages and I didn't get any woodland mansions. The worlds they give me are plain and boring. With the console edition, I get a colorful world full of various biomes, villages, caves, strongholds, mansions, etc but Minecraft pocket edition only give me 1 boring land type. Any way to enable all biomes for a world or is there a setting I need?