You already found that you can set "Seconds to jump" under
(rightclick >) Options > Preferences > General
(at the bottom of the centre grey "column" to the right of the [Close] button)?
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P.S.: some related possibilities/shortcut keys (only "forwards" mentioned):
Code:
[F5].............Increase playbackrate by 1%
[Shift]+[F5].....Increase playbackrate by 10%
[Ctrl]+[F5]......Fast forward
[.] (=period)....Jump forward
[Ctrl]+[J].......Jump to time
[arrow right]....Seek forward