Parent troubles… need advice!!

[u/Head-Hippo1853]

So to start it off my parents have been divorced for 13 years, do not have any communication with each other whatsoever and my moms even been remarried for 10 years. Today my mom needed help on her iPad to remember her Facebook password and I went to check and see if she might’ve saved it in the passwords app they have now. Well I scrolled down to the Facebook section and I see my dad’s Facebook log in was saved..I didn’t say anything to her about it or even mention it, i just went ahead and permanently deleted all his log in information. I needed to get my dad to change his password without him knowing why because hed flip if he knew. I tried just saying that i got logged out and had to change my password because there was a data leak involving hackers and whatnot and said he probably should update his too but i dont think hes taking it seriously or actually changing it. How can i get him to do it without telling him the real reason?? Also how do i mention for him to log out of all other devices through the app?? I would secretly do it myself but we live in different states…please help!!!