1) You'll need NBTExplorer.
To Download the program go to this link:
https://github.com/jaquadro/NBTExplorer/releases/tag/v2.7.5-win  (Download the zip file) 

2) Extract the zip file.

3) Open the folder and run NBTExplorer.exe

4) When NBTExplorer is open click on File then Open.

5) Then goto: AppData\Roaming\.minecraft\saves

6) Now open your Level Folder Name that you would like to change the colour of.

7) Then open the file "level.dat"

8) Click the + button next to the name "Data: 24 entries"

9) Double Click on LevelName:

Ok, now you are up to colouring your level name.
To colour your level name you'll be using the symbol: §
Ok now for an example, if your level name was MinecraftWorld and you would like to change it to DarkBlue
you would have to put  §1 before your level name with no spaces between them so it would look like: §1MinecraftWorld

Here are all of the colours that you can use:

Code	Official Name	Foreground Color	Background Color
R	G	B	Hex	R	G	B	Hex
§0	Black	0	0	0	000000	0	0	0	000000
§1	Dark Blue	0	0	170	0000AA	0	0	42	00002A
§2	Dark Green	0	170	0	00AA00	0	42	0	002A00
§3	Dark Aqua	0	170	170	00AAAA	0	42	42	002A2A
§4	Dark Red	170	0	0	AA0000	42	0	0	2A0000
§5	Dark Purple	170	0	170	AA00AA	42	0	42	2A002A
§6	Gold	255	170	0	FFAA00	42	42	0	2A2A00
§7	Gray	170	170	170	AAAAAA	42	42	42	2A2A2A
§8	Dark Gray	85	85	85	555555	21	21	21	151515
§9	Blue	85	85	255	5555FF	21	21	63	15153F
§a	Green	85	255	85	55FF55	21	63	21	153F15
§b	Aqua	85	255	255	55FFFF	21	63	63	153F3F
§c	Red	255	85	85	FF5555	63	21	21	3F1515
§d	Light Purple	255	85	255	FF55FF	63	21	63	3F153F
§e	Yellow	255	255	85	FFFF55	63	63	21	3F3F15
§f	White	255	255	255	FFFFFF	63	63	63	3F3F3F

Also you can use Bold, Italic, Strikethrough, Underline, Obfuscated and Reset
Also just to let you know Reset is used to Reset the Formatting Codes that you've used before.
An example of using Green, Blue, Bold and Reset: §a§lMinecraftWorld's §r§9§lCool
Also if a colour code is used after a formatting code, the formatting code will be disabled beyond the colour code point.

Here are the Formatting Codes that you can use:


§k = Obfuscated
§l = Bold
§m = Strikethrough
§n = Underline
§o = Italic
§r = Reset

Ok so now you're pretty much done.
Example of the Level name done: §5§lMinecraft§r§4§oWorld
When you're done renaming your World click Ok then click File then Save.
Now go back into Minecraft and go to the Title screen then back to the World Selection.
You should see your Minecraft World Coloured ect.
If not simply read over these instructions again.

If this Tutorial helped you, please Diamond and Favorite.
If you need any help please feel free to comment below!