Why i cant change secondary template color ?

First be sure that you follow the corect steps. Go to SH Admin > General settings > Custom website color - click on field. You can insert the color in hex code manually or you can use the collor picker, and click on color fountain (lower right side), dont forget to check Update color palette on save, and Save settings. If the color does not change check, if you have writing permission on color.css file located in simple-hosting/dynamic foloder