Just thought I'd add a bit of clarity as to how to unlock this achievement.
In order to unlock this achievement, first press
to access your Heroes, and then select one, then select 'Customize', then press
.
To change your color swatch, you just have to select 'Colors' and then choose one you're not currently using. To change your hero's Symbol and Paint Pattern, you must first select a body part (for example, the right shoulder), then change the Symbol and Paint Pattern under their respective tabs. Once you've changed all three, the achievement should unlock.