Want to connect apps on firestick to cable subscription on different Verizon account

Hello,

I have Fios internet and an Amazon firestick. Previously, when I would open an app and select a cable provider I could choose verizon and then manually log into my DIFFERENT verizon account than my fios internet account. Now, the app automatically logs in to the verizon account associated with my internet and does not allow me the opportunity to manually log in. Unfortunately I do not have cable associated with my wifi account and am now unable to use the MTV app... Do you have a work around to allow me to manually log in? A code I can use to go to mtv.com/activate to use my proper cable login? Thanks!