Hey Erwin,
I actually think that your website configuration is not properly setup and that is why you see the wrong time.
Please make sure to set up the correct timezone. Once you've done this please test it with the Article manager.
Create a new dummy article (title = test time, content = teset) -> click save and look on the right -> does it show the correct saved time? If it doesn't it means that matukio will also not show the correct time.
So in matukio if you create a new event with title:
"Event 20 april 17:00 - 19:00"
and you set up start time 17 and end time 19 and you save this event -> is it shown with the correct time in the backend? If it is not, then it means that your timezone is not properly configured.
In the frontend if you are not logged in -> it should show the time with timezone applied from the global configuration. If you are logged in, it will take the timezone from your profile settings, provided that you have set a timezone. If you haven't set up a timezone in your profile settings, then the global config will be taken.
Again -> if you see different time from the one you entered for start and end time it means that something is not properly configured on your server -> wrong timezone, wrong timezone in the user profile etc.
Kind regards,
Daniel