Replacing old WP on sub-domain w/ new WP from a sub-folder in Primary domain

Backstory: I was running an old version of WP, (it’s still running now), and I desperately needed to update everything so I built a new version of my monitized blog in a subfolder under the primary domain and now I can’t get it to replace the old one without all the links resulting in a. “404 page not found,” error.

BlueHost has tried to help me twice with this and as I write this, they are restoring all of my data from their backup copy, again, (ever see a monkey f**k a football?)

OK, 1) primary is <thefundamentalist.info>
2) old sub domain is <opportunities.thefundamentalist.info>
3) the new site I built as the replacement is in
<thefundamentalist.info/new-opp>

I’m dying here! I really need the 3rd grader’s version of, “Doing what should be simple to make things work – For Dummies.”