How can I feel safe from a Trojan Attack?

Hello, I'm not that techy guy. But knows how to run a computer. But then I've experienced this rookie mistake. I've downloaded a malicious program a .exe which is I didn't thought as. After I installed my pc detected it as a Trojan and I immediately block it and delete the installer. I haven't had the time to screenshot the prompt, as I immediately blocked i. After that I ran scan using my windows security and found no threat. I'm still not complacent after what happened. I bought premium bitdefender to ran different scans. System scan, vulnerability scan, as well as quick scan every day after I open my pc. I tried contacting a techy friend to find any random files which has letters, numbers and special characters file name inside the %appdata%

I'm still worried how can I know if I'm really safe and free

Answers