Hi @ColruytTeam and Raj!
Taking a step back, we recently made some changes to the app UI - including the Toolbar - as part of a more general ‘pruning’ effort.
We have removed a number of icons from the Toolbar and, right now, there’s no setting or option to toggle between the new Toolbar and the old Toolbar.
Note that, the features have not been removed - just their icons in the Toolbar. You can still find all of those features in the app:
You can find the Copy, Duplicate and Paste items on the main menu (and also on the right-click context menu when you select a control then hover over the canvas to paste):

Group and Ungroup are also on the menu now: Edit > Group ; Edit > Ungroup . They are also on the right-click context menu.
Arrange, Align and Lock are all on the Edit menu now:

And there are also alignment controls in the Property Inspector which appear when you have multiple controls selected:

The Zoom buttons are now menu options:

And, finally, the Markup option is now in the menu:

Note that if you toggle the Markup option off , a Show Markup button will then appear in the Toolbar.
And, there are keyboard shortcuts for all of these items to save you having to use the menus(s) each time.
We hope that, while this change may feel a little odd at first, you’ll find the app simpler and quicker to use in general.
Finally, if this change is really causing you problems, get back to us and we can discuss. We track all product and feature feedback formally and I’ve already gone ahead and added your feedback to our tracking for this change.