Hi there @Sarai1!
Don here from Shopify.
Would you mind sharing a link to your store with me here so we can check this out together?
If you could also confirm which payment gateway or gateways you have enabled for your store, that would be great.
Finally, for now, could you share any other info your customers reported from their attempts to check out?
You just mentioned that the options were not available to them there; would they have encountered any errors or messages when trying to check out or the option to pay is simply not showing for them there?
If you can share the store link and info requested above, we can look into this for you to see what we can see.
Have you just recently set up your store, or have you been selling for a while already?