Very often newly planted palm will go through so called “transplant shock” caused due to roots being disturbed and exposed to air and sunlight. When you move a palm tree, it loses a lot of its roots resulting in water loss in the foliage.
So, it’s normal for a newly planted palm to have brown, yellow or droopy leaves while it’s recovering. It could also be due to acclimatization to the new light levels, humidity and temperatures. Here is what to do:
Keep watering the palm.
Avoid fertilizing it.
Don’t prune any of the dying leaves until they are completely dry because palms move nutrients from the dying leaves to the new growth.
Droopy leaves might be a sign of bad drainage. What kind of soil do you have? Have you used a soil mix when planting the palm? You can read about improving drainage in more details in my article on planting palm trees.
If after a few weeks it’s still not doing well, it might have been damaged during transplanting or planted it too deep.
Check the depth. If the root ball has dropped, you might have left air pockets in the soil when backfilling the hole. And now the palm is sitting too deep. You will need to re-plant it.
If the tree was damaged, spray it with Copper Fungicide to prevent fungi and bacteria from developing.