The View Menu

Zoom in

Enlarges the structure(s) painted.

Zoom out

Scales down the structure(s) painted.

Zoom 100%

Zooms to the original size.

Clean Structure

This lays out the structure according to standard rules (Structure Diagram Generation).

Flip horizontal/vertical

Flips either the selection or the complete structure (if no selection is done) around the horizontal or vertical axis.

Implicit Hydrogens On all/Off

Here you can show hydrogens on all or no atoms. Note these are settings which can also be achieved by choosing "Explicit Carbons" and "Show implicit hydrogens" in Edit->Preferences.