Opera Next 15 is not the old Opera browser any more, it’s now based on Chromium with Blink  engine instead of Presto. Opera has already announced about three release channels it going to offer and upcoming new features coming in future versions. You may need to start all over again in adopting to new Opera- the UI, settings, Off-Roadmode, keyboard shortcuts etc. Though some old keyboard shortcuts might work here is complete list of keyboard shortcuts for Chromium-based Opera.

Opera 15 (chromium-based) keyboard shortcuts

            Action    Shortcut
Open Downloads page    Ctrl +J
Open Extensions page    Ctrl +Shift +E
Open local file    Ctrl +O
Open location   Ctrl +L
Open Settings page   Alt +P
Print current page   Ctrl +P
Quit Opera   Ctrl +Shift ⇧ +X
  Save a page locally   Ctrl +S

  Cycle forward through page

  Windows +Tab
Cycle back through page elements   Windows +Shift ⇧ +Tab
Go forward one page   Ctrl +→
Go back one page   Ctrl +←
Find on page   Ctrl +F
Find next   Find next
Find previous   Ctrl +Shift +G


Read Keyboard Shortcuts to Switch between Tabs in Chrome

Internet Explorer 9 Keyboard Shortcuts