Application - per user settings (existing & new)

Question

Hey

with a range of IT restrictions in the registry which is where i was intending to store data, what else is a good secure method storing data per user? it must be per user because each user will work on different projects so things like the last job no, the crm login & password would need to be stored independently. Also, it must work with any existing users who has logged onto the machine as well as new users who are logging on for the first time.

I see that app.config & user.config already exist, does user.config work for new & existing users?

app.config gets copied to the output folder renamed as the app.exe.config which i can include in my installer but what about the user.config? does that self generate as settings change?

My biggest obstacle is the connection string, userUD & crm password. While i am storing the UID & PD as an encrypted string, the connection string is not. what i good secure way of working with a connection string storage? I read that i can add it to separate config file and reference that file in the app.config but its still just a text file at the end of the day.

is there a secure or alternative or reasonable method to achieve my objective? It could be a case of me understanding how the config files work per app / user etc

Thanks