You can't at the moment.
This board has had a software update about a half a year ago, but that didn't go as well as people hoped for.
Some stuff has been under investigation by the software manufacturer, some improvements have already been tested but not all with satisfying results.
One of these problems is that you'll have a very hard time to edit your profile, which is where you should be able to do this.
You can try however:
Point on the profile (the icon that shows a shadow of a person in your case), next to the shopping cart on the top right of this page.
A drop down menu will appear, the top item is "profile", click that.
Now you'll see a page showing your profile info.
On the top left, a button called "Settings" is visible.
Point there and select "Look and Layout".
On the next page you can see the timezone you're supposed to be in, you'd probably need to correct that.
While you're there, check the other items on that page.
After you're done, click "Change profile" on the bottom right.
If you're lucky it will work.
If you're even more lucky it will still work tomorrow.
If your luck has been used up today, it won't work and you'd have to try again whenever you feel particularly lucky.
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DO NOT SHOUT !!!
And be patient waiting for answers.
Also do not expect administrators to answer your questions, they may very well be busy doing some more important things than attending to some small annoyances (as described above).
This is a worldwide forum that has its roots in Italy.
Today is a holiday and we're just after midnight right now here in Europe.
And certainly never expect answers within a few hours anywhere on this board.
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