How to solve the "Large displacement" issue in COS

I am quite new with COSMOS, using a COSMOS Professional. I am just wondering how to avoid the message saying “The load creates a large displacement. Do you want to activate the large displacement flag…” . I am working within linear range.

And also, what should I do if i have this message “Equilibrium satisfaction not achieved. Save results up do current iteration”. If I click “yes”, are the results I get all wrong?

Please advise…Thank you in advance.