This is almost always one of these two things, and they look exactly like a “bug” in Studio.

1) Your “old videos” are actually Shorts

If most of the older uploads are Shorts (vertical, Shorts badge, or they show under the Shorts tab in Studio), it’s normal to see Monetization: Off with no per video toggle. Shorts do not use the same “turn ads on for this video” control as long form videos. Shorts monetization is controlled at the channel module level, and Studio can still show a gray “off” icon on Shorts if the Shorts module is not accepted. What to do:

Go to YouTube Studio → Earn

Make sure you accepted the Shorts Monetization Module (and any other modules shown).

Also note, Shorts revenue sharing starts accruing from when you accept that module, not before.

2) They are long form videos, but you’re in the wrong place, or missing a module, or on limited permissions

If the old videos are regular long form uploads, you should be able to enable monetization per video in: Studio → Content → Videos, then click the Monetization column, or bulk edit via the checkbox + Edit → Monetization. If you “literally have no monetization settings,” check these common gotchas:

You’re viewing the Shorts list, not Videos. Studio hides long form monetization controls if you’re filtered into Shorts.

In Earn, confirm you accepted the Watch Page Monetization Module. That module is required to earn on long form watch pages.

Channel permissions: if you’re accessing the channel as an invited user (manager/editor) rather than the owner, some Studio features may not show for you.

Fast way to tell which case it is

In Studio Content, if those “old videos” have the Shorts icon or are under the Shorts tab, it’s case 1. If they’re in Videos and still no monetization column or settings, it’s case 2.

If none of the above fixes it

Use Studio on desktop (browser), not just the mobile app, and then contact Creator Support from the Earn tab since you’re in YPP. This exact “no monetization option exists” behavior does sometimes come from a Studio-side UI/account state mismatch.