Hi Ddearing ,
My sincere apologies for the inconvenience caused.
I am afraid,the regular checkbox check color cannot be changed.But I have created a feature request for changing the color of the checkBox.
We will try our best to implement this at the earliest. You can track the status of feature here.
Feature Request #892 - Add property to change the color of the checkBox .
We will inform you as soon as this feature request is addressed.
Thanks for your interest in Syncfusion products.
Kind Regards,
Deepa.