Edit Source in SDL Trados (2011 and later) - Alt+F2

[spiros]

Edit Source in SDL Trados (2011 and later versions) - Alt+F2

Alt+F2 or right click in segment and select Edit source. If greyed out  it is locked down but you can make it available through Project Settings > Project, select Allow source editing for supported files.

More here:
What’s all the fuss about “edit source”? | multifarious
https://docs.sdl.com/LiveContent/content/en-US/SDL%20Trados%20Studio%20Online%20Help-v3/GUID-903C6626-C4A8-421D-84BE-D65EF32853B2