Shift the start time of the current timing unit backward

`Num 4`

All hotkeys for Aegisub

Default Exit the application	`Ctrl` + `Q`
Default Configure Aegisub	`Alt` + `O`
Default Find and replace words in subtitles	`Ctrl` + `H`
Default Copy subtitles to the clipboard	`Ctrl` + `C`
Default Cut subtitles	`Ctrl` + `X`
Default Split the current line into a line which ends on the previous frame and a line which starts on the current frame	`Ctrl` + `Del`
Default Paste subtitles	`Ctrl` + `V`
Default Paste subtitles over others	`Ctrl` + `↑ Shift` + `V`
Default Split the current line into a line which ends on the current frame and a line which starts on the next frame	`Ctrl` + `↑ Shift` + `D`
Default Redo last undone action	`Ctrl` + `Y`
Default Undo last action	`Ctrl` + `Z`
Default Move to the next subtitle line	`Ctrl` + `Num 2`
Default Move to the previous subtitle line	`Ctrl` + `Num 8`
Default Move the selected lines down one row	`Alt` + `↓`
Default Move the selected lines up one row	`Alt` + `↑`
Default Help topics	`F1`
Default Search for text in the subtitles	`Ctrl` + `F`
Default Find next match of last search	`F3`
Default New subtitles	`Ctrl` + `N`
Default Open a subtitles file	`Ctrl` + `O`
Default Save the current subtitles	`Ctrl` + `S`
Default Save the current subtitles	`F2`
Default Save subtitles with another name	`Ctrl` + `↑ Shift` + `S`
Default Shift selection so that the active line starts at current frame	`Ctrl` + `6`
Default Shift subtitles by time or frames	`Ctrl` + `I`
Default Set end of the selected subtitles to current video frame	`Ctrl` + `4`
Default Set start and end of subtitles to the keyframes around current frame	`Ctrl` + `5`
Default Set start of selected subtitles to current video frame	`Ctrl` + `3`
Default Toggle focus between the video slider and the previous thing to have focus	`Ctrl` + `Space`
Default Seek to the next frame	`Ctrl` + `Num 6`
Default Seek to the previous frame	`Ctrl` + `Num 4`
Default Jump to frame or time	`Ctrl` + `G`
Default Jump the video to the end frame of current subtitle	`Ctrl` + `2`
Default Jump the video to the start frame of current subtitle	`Ctrl` + `1`
Default Play video starting on this position	`Ctrl` + `P`
Default Zoom video in	`Ctrl` + `Num +`
Default Zoom video out	`Ctrl` + `Num -`
Audio Toggle global hotkey overrides (Medusa Mode)	`Ctrl` + `Num *`
Subtitle edit box Move to the next subtitle line, creating a new one if needed	`⤶ Enter`
Video Scale subtitles on X and Y axes	`G`
Audio Play audio until the end of the selection is reached	`↑ Shift` + `G`
Audio Play the audio for the current line	`R`
Audio Play audio until the end of the selection is reached	`Space`
Audio Play 500 ms after selection	`W`
Audio Play 500 ms before selection	`Q`
Audio Play first 500 ms of selection	`E`
Video Rotate subtitles on their Z axis	`D`
Audio Play from selection start to end of file	`T`
Audio Play selection, or stop playback if it's already playing	`B`
Video Standard mode, double click sets position	`A`
Video Rotate subtitles on their X and Y axes	`F`
Video Clip subtitles to a rectangle	`H`
Audio Add the lead in time to the selected lines	`C`
Audio Add the lead out time to the selected lines	`V`
Audio Decrease the length of the current timing unit	`Num -`
Audio Decrease the length of the current timing unit and shift the following items	`↑ Shift` + `Num -`
Audio Increase the length of the current timing unit	`Num +`
Audio Increase the length of the current timing unit and shift the following items	`↑ Shift` + `Num +`
Video Seek to the next frame	`→`
Audio Next line or syllable	`X`
Video Seek to the previous frame	`←`
Audio Previous line or syllable	`Z`
Subtitle edit box Move to the next subtitle line, creating a new one if needed	`num⤶ Enter`
Always Play audio until the end of the selection	`Num 5`
Always Play 500 ms after selection	`Num 3`
Always Play 500 ms before selection	`Num 1`
Always Stop audio and video playback	`Num 8`
Always Decrease the length of the current timing unit	`Num 7`
Always Increase the length of the current timing unit	`Num 9`
Always Next line or syllable	`Num 2`
Always Previous line or syllable	`Num 0`
Always Shift the start time of the current timing unit backward	`Num 4`
Always Shift the start time of the current timing unit forward	`Num 6`
Translation assistant Play audio until the end of the selection is reached	`End`
Translation assistant Move to the next line without commiting changes	`Page Down`
Translation assistant Move to the previous line without commiting changes	`Page Up`
Translation assistant Commit changes and stay on the current line	`F8`
Translation assistant Play current line	`Home`
Translation assistant Insert the untranslated text	`Insert`
Subtitle edit box Set the outline color (\3c) at the cursor position	`Alt` + `3`
Subtitle edit box Set the primary fill color (\c) at the cursor position	`Alt` + `1`
Subtitle edit box Set the secondary (karaoke) fill color (\2c) at the cursor position	`Alt` + `2`
Subtitle edit box Set the shadow color (\4c) at the cursor position	`Alt` + `4`
Subtitle grid Select all dialogue lines	`Ctrl` + `A`
Video Seek to the next beginning or end of a subtitle	`Ctrl` + `→`
Video Seek to the next keyframe	`↑ Shift` + `→`
Video Fast jump forward	`Alt` + `→`
Video Seek to the previous beginning or end of a subtitle	`Ctrl` + `←`
Video Seek to the previous keyframe	`↑ Shift` + `←`
Video Fast jump backwards	`Alt` + `←`
Video Drag subtitles	`S`
Video Clip subtitles to a vectorial area	`J`