Pets.. they pushed my buttons last night

I got this cute kitten as a birthday present from 3 of my grandkids. She's loveable and cuddly and tolerates being mauled by the dobie. My only problem is dealing with her potty habits. She uses her 2 litter boxes if she's confined to the room I keep her in at night and when I'm at work. However when she's out with me and Katy, if she has to potty she won't go to her litter box. She gets under an end table next to the couch and loveseat and craps. Not the harder kind that would clean up easily... noooo.. the super smelly hard to clean up kind. Any suggestions on how to get her to stop this habit? Last night she had me so upset with her... then after going to bed, sometime during the night, Katy peed on my bed. She's house broken and had gone out before we went to bed. I guess she realized I was upset and it was upsetting her too... who knows.. but I'm doing laundry and having to stretch out comforter and blanket while I'm working so they'll hopefully be dry by the time I go to bed tonight... Sighssssssssssssssssss