When Select Category need to pre-select other checkbox

Will do 1- milestone of $15.00 not more will pay at end upon completion..NOT hireing no-one over my pay price.. Have 2 quick fixes i need....... (1.) Need a code script done to for when a certain category is selected it will preselct other checkbox... Need when the category named "Private Category " is selected i want to pre-select the checkbox Private Lock checkbox...Don't want the private Lock checkbox to be usable except pre-selected when used with Private Category.....SEE shot.. I know some files of the pages and have others in hand.. I will send files for you to edit them then send back.. I will send site link so you can see work.. Don't send your mile long links to me, message me about my project.. Don't ask for C/panel credentials, work with files alone..