Hi Mary Jane

Thanks for reaching out to Ask Extension! 

If you are willing to provide some more details, that could help with identification of the issue. The leaf yellowing and stippling makes it appear you could have a pest such as spider mites. Are you able to see any webbing? Any small critters roaming on the leaves? If so, regularly rinse plants with water to keep down spider mite problems.
Use a registered houseplant spray to control mites. Plants damaged by heavy mite feeding can be injured by insecticidal sprays. Severely damaged plants should be discarded.

To be sure, I would suggest that you submit this question to the MSU plant diagnostics lab:  <personal data hidden>. They can advise you further to make sure we id the right thing and that you know how best to treat the plants. Here is a link to their webpage:

https://www.canr.msu.edu/pestid/

If you are interested in doing some further diagnostics yourself, here is a link to a good tool:
https://extension.umd.edu/resource/diagnose-indoor-plant-problems/