Check and configure your digital security.
You can run a security check of your computer on the Swiss Internet Security Alliance website and will also be able to obtain information on current security threats there.
The BSI webpage will help explain the most important security settings for different types of web browser.
When looking for your personal compromise, the c't website should be of some help. It will explain the individual browser functions and also demonstrates their potential for abuse.
The Microsoft website will advise you on the security settings you should activate to use specific programs.
This Mac website will advise you on the specific points you have to look out for with your Mac.