You can definitely modify LLSPs to different times
and attractions.
Here's what the Disneyworld website says:
Modify Your Plans
Changed your plans… or your mind? You can modify your
Lightning Lane selections via the My Disney Experience app.
To get started, tap the Lightning Lane Passes section on the app’s home screen to find your plans. Then, you can:
- Change your selected park and/or date in advance (subject to availability)—up until the moment you redeem your first Lightning Lane selection of the day.
- Change each selected experience and/or arrival window in advance (subject to availability)—up until the start of the arrival window
That's from a webpage dealing with both multi pass and single pass:
https://disneyworld.disney.go.com/lightning-lane-passes/#drawer-card-DrawerHowToPurchaseLL
See the Molly video at:
At 24:36 or thereabouts, she describes modifying LLSPs. At 25:16 is a screenshot listing the prices to change Seven Dwarfs Mine Train to Avatar, Tron, or Guardians that day. (I assume Rise was not then available.) As expected with Disney, you have to pay more to switch to the more expensive attraction, but don't get money back if you switch to a less expensive attraction.
Molly was only showing changes to another attraction on the same day, but I'm pretty sure you can also switch to another day.
Jennifer of Touring Plans says: "The workflow for modifying a Lightning Lane Single Pass is similar to modifying for a whole Multi Pass, shown above. But, there are a few things to note. First, you’ll only be able to modify if there is availability (Duh!). Second, like with changing your Multi Pass date or park, you’ll need to pay the difference if your new selection costs more. And, just like with Multi Pass, if your new selection is cheaper you do not get a refund." Source:
https://touringplans.com/blog/how-t...disney-world-guide-faq-llmp-llsp/#single-pass
I think the "date and park" language means you can switch your single pass to another date, but that may just be my interpretation. I interpret the language from the Disneyworld website similarly.
Edit: Corrected which LLSPs were and were not available on Molly video.