How to level up your World in Borderlands 2

While I'm not familiar with this tool that you've used, I assume you were in your first playthrough. During the first playthrough, enemies only get up to around level 35. Once you've finished that playthrough by

killing The Warrior

You will unlock the next playthrough, True Vault Hunter Mode. During this playthrough, enemies start at approximately level 34 and go all the way up to level 50. Once the playthrough is completed, all enemies will be level 50. The Borderlands Wiki highlights other ways enemies are different besides level (summarised by me):

• Increased Enemy Health
• More Badasses
• New Enemies
• Better Loot
• More XP from missions

In both of these modes, enemy level is based on the zone that you're in.

Once you complete this mode (in the same manner as the first), you will unlock a third playthrough: Ultimate Vault Hunter Mode. In this playthrough, enemies just scale to the highest level in the party (during solo this will be your level). The enemies always scale to the level of the highest party member, regardless of area that you are in (unlike the other two modes).

The reason you are only seeing enemies up to level 36 is because you are probably in the first playthrough still. You will need to play through the main story, and complete this playthrough to unlock subsequent playthroughs where enemies and loot will be higher.