Why suspicious activity ruined my week ?

A few days ago I noticed some unusual behavior in my accounts, like logins from unknown locations and random changes I didn’t make. At first I thought it was just a glitch, but then I realized something might actually be wrong. Now I’m constantly checking everything and it’s making it hard to focus on my work. I don’t even know if I’ve already fixed the issue or just missed something important. What’s the best way to make sure your digital stuff is actually safe after something like this happens?