The Diff Appearance preferences panel is opened from menu Diff+Appearance
→ +If checked the lines presented in the two diff panels are wrapped at the right margin of each panel so that no horizontal scrollbar is necessary.
The color used for incoming changes on the vertical bar that shows the differences between the files compared.
The color used for outgoing changes on the vertical bar that shows the differences between the files compared.
The color used for conflicts on the vertical bar that shows the differences between the files compared.