how can i automatically update a contacts field when i edit or add a certain field in Accounts module?

how can i automatically update a contacts field when i edit or add a certain field in Accounts module?

to better help with my email marketing, i have created a few different check boxes under the contacts module to help sort different customers. 

I am finding it very tedious to enter in all this information twice, because i have to add the data to the account module and then also add it in the contact module. 

So, my question is, how can I create a rule, that when i update a certain field in the accounts module, it will automatically update the contacts module? (updating all contacts in that account would be perfect)

Thank you