You don't need to set countries for 1c ads, they will only ever be shown in the low cost countries and whilst you will get the views, those views are almost useless.
Those people won't subscribe or watch more of your video's, and most likely you will get a large % of thumbs downs and very low page rpm.
It's best to target the audience you want so a 5c ad will get better countries which in turn are more likely to subscribe and keeps your page rpm up.
Going for the more higher paid countries would take 10c - 12c ads, norway, saudi arabia, dubai etc might sound expensive but if they sub and watch your video's you will notice a much higher page rpm, works both ways, advertise to high end countries gets you high end views.
I would much rather 10 subs from norway then 1,000 subs from vietnam or india.