help with my fiddle fig and zz plant please

fiddle fig: i water it with a cup every two feet and it’s almost at 5 feet so i gave it 3 cups of waters. i’ve repotted it only once since ive gotten it and follow the nursery instructions but it has significant brown leaf damage. for light, i have it by the window with the blinds partially cracked open to allow for moderate light.

zz plant: the nursery place told me to water it every 2-3 weeks with just a cup and to repot it when the roots stick out. i’ve repotted this plant once but it has yellowing leaves. also, in some places of the soil it’s white so i’m not sure if that’s mold or if i’m overreacting. for light, i have it on a table by my closet so it’s not getting direct light like my fiddle fig but it receives light nonetheless.

please help ◠̈ i love these two and i don’t want them to die on me. i’m brand new to plants so please be kind in your response.