Certificate = an official document attesting a certain fact, in particular
Select a certificate to authenticate yourself. Help!
1. Open KeyChain Access
2. Go to My Certificates
3. Find the relevant certificate and double-click to open
4. There’s a Trust section that’s closed by default, open it to expose the dropdowns
5. Under “When using this certificate”, select “Always Trust”
6. Close everything and try refreshing the web page, you should no longer get the window to select a certificate