Preselected Checkbox and Text Display

I would like to know where I can set the code to have the mailing list checkbox preset to “yes” and where I can change to text title “Join our mailing list.” to read something else and flush left rather than center it.

I assume this is in the mailchimp add on PHP code file. Or, is there some other way to do it so it is not overridden during future upgrades.

Rick

https://ww.wp.xz.cn/plugins/pmpro-mailchimp/