Download NBTExplorer 1.15 for Minecraft
NBTExplorer is an NBT data editor. With this program, you will be able to open your map and change various parameters, as well as make a color name for your map.
How to make a colorful name with NBTexplorer
In the program open up your world
Find the LevelName option
Using formatting codes, name the map
For example: §4Cool §6Dom
How to install NBTExplorer
Download and unpack archive
Press File→Open and select a folder with the map.