I say cut off all those yellow fronds. Don't sap any more energy from them than needs to be. Elaine had great advice for you. Sago palms happily grow in partial shade or what I will call Florida's partial shade which means a whole lot of sun, at least 6 hours and they will grow in the full, relentless FL sun which means up to 14 hours of sun. I think yours are getting too much shade. Also the other things that Elaine said. Dig them up & move them if you want to save them. Put them in the yard where they get more sun & cut everything yellow off NOW. Cut it right back to the trunk there.
It will likely take a long, long time for you to see new growth on them so you will have to be patient and wait. They may or may not survive.
It may be too hard to get them out of that narrow planter with enough roots left on them to give them a fighting chance.
I wish you luck!
