Hi Ginger,
How near a window is your Pachira? They need bright indirect light - directly in front of a window that doesn't receive direct sunlight is best. Our pupils adjust to light changes so rapidly we don't always perceive it but the amount of available light decreases drastically even a few feet away from a window.
Soft stalks are indicative of a serious root problem. Have you repotted the
plant into a larger pot since acquiring it? If you only need to water the
plant once a month the soil is staying wet too long which leads to root rot. Conversely, if the
plant dried out too much the roots might have shrivelled and don't hold water anymore. It might already be too late but a suggestion is to gently remove the Pachira from its pot to inspect the roots. Trim away all black, brown, mushy or shrivelled roots. If there remain any firm white roots, pot into the smallest pot that will hold the rootball and only water when the top 1/4 of soil is dry.
Houseplants generally do better when they are moderately rootbound - unless the
plant requires watering more frequently than every 3 days, you are better to leave it in its original pot. Repotting often leads to overwatering and root rot. If the soil doesn't dry out within 2 weeks it means the pot is too large.
Avoid fertilizing the Pachira. Even healthy houseplants consume very few nutrients, less when they are ailing. Fertilizers are not medicine and should only be given to healthy, actively
growing plants.
Welcome to The Garden Helper.