Then you can say that you have some accounts but you don't remember the password anymore: "I'm just logged in from my computer at home. If I delete the cookies I don't know if I would be able to get the password again"
This is genuinely applicable to me. I don't remember any of my passwords since I'm logged in at most places via cookies, and my passwords are completely randomized strings two dozen or more characters long, stored in a password manager.
Do border security understand how password managers work, or would I have to tell them how to access my own data?
Showerthought: If I delete my password manager from my phone, maybe the password manager should perform geolocation and detect if the application is trying to be installed at an airport (possibly indicating installation against my will). That's a very nuanced situation.
I suspect they understand how password managers work and either ask you for access or take your hardware and fiddle with it off-screen (Evil Maid attack? [0]). Otherwise if they don't like you they just send you back home and that's it.
1. Lying to them falls under "fraudulent access to the USA" and the penalty is permanent exclusion, no Visa will help you, you have no right to appeal.
2. You cannot discuss or appeal anything, there isn't a discussion that you are a part of in which you get to explain your side or proffer an excuse... your actions already did your talking.
Don't lie to border control, don't give BS excuses. Either you're willing to give them access or you shouldn't have boarded the plane. "I can't because I don't remember" is not a right to enter the USA... you do not have that right, the right is granted by them.
Do border security understand how password managers work, or would I have to tell them how to access my own data?
Showerthought: If I delete my password manager from my phone, maybe the password manager should perform geolocation and detect if the application is trying to be installed at an airport (possibly indicating installation against my will). That's a very nuanced situation.