Timeline Controls II
There is a column of controls on the left of the Timeline.

I centers the current position on the Timeline.
+ zooms in.
= sets the Timeline at the standard zoom setting. (If the Timeline is already set at the standard level, this symbol is blue and non-active. If the Timeline has been zoomed in or out, this symbol changes to red and becomes active. Clicking on the red equals sign will return the Timeline to the standard zoom level.)
- zooms out.
The clock and film symbols allow you to switch the calibration of the Timeline between playing time and the number of frames.
The circular arrow allows you to play a chosen sequence on repeat. (To set stops see Timeline Controls III)
The music symbol and the picture symbol can be used to suppress audio or video during preview.
More Timeline Controls
Video editor