I'm using the latest Matomo self-hosted version. Is there a one click solution to set all settings to be GDPR compliant? (like import default settings for GDPR)
GDPR can be a complex process, there is this guide that goes over the 12 steps: https://matomo.org/blog/2018/04/how-to-make-matomo-gdpr-compliant-in-12-steps/
The easiest way to be compliant with GDPR easily is to not collect any personal data with Matomo, learn how at: https://matomo.org/blog/2018/04/how-to-not-process-any-personal-data-with-matomo-and-what-it-means-for-you/
@mattab is completely right. I just wanted to add a bit more detail.
The GDPR covers the processing of "personal data". If what you collect is not "personal data", you can consider yourself to be compliant with the GDPR. But that requires a bit of sacrifice: You will obtain less detailed, less precise information. The most immediate example is IP addresses and GeoIP results from those addresses. Full IP addresses are considered "personal data" because a natural person can theoretically be identified from it. And GeoIP information from full IP addresses are also very likely to be considered personal data. matomo has options to deliberately reduce the information in IP addreses and location data from it, so that it can be considered "anonymous" (and therefore not "personal data")
If you cannot stomach that, you will be processing personal data. And then being "GDPR compliant" requires a lot of consent management, privacy policies, data deletion policies etc. etc. As someone running a site on a no-personal-data basis, I can say that you still get a lot of interesting and useful data without it being personal.
The matomo guide linked to by @mattab is helpful if a bit sparse on the whys and wherefores. (selfpromotion) I have written a more detailed guide to matomo without "personal information" if you would like to know more than just what buttons to press and what it means for the quality of your data (/selfpromotion).