Every Origin graph window is constructed using a graph template -- either built-in or user-modified. The contents of every Origin graph window are organized in a Page > Layer > Plot hierarchy, with the page at the topmost level (represented by the Graph1 icon in this figure showing the left panel of the Plot Details dialog box).
Each object in this page-layer-plot hierarchy has associated objects and/or properties. It will be helpful for you to develop some sense of which objects and properties are logically associated with each level in this Page > Layer > Plot hierarchy. Note that each Layer and Plot has a checkbox to its left which allows you to Show (checked) or Hide (unchecked) that element.
At the risk of stating the obvious, we will note that any property of the graph page will apply to all graph layers in that page and any property of the graph layer will apply to all plots in that graph layer. At the plot level, we will modify this to say that any property of the plot applies to all data points in that plot except where the properties of a single data point have been customized (applies only to 2D scatter and line & symbol plots).
In addition, note that Origin has several page viewing modes which help you to either have faster screen redraw speed or have more graph display accuracy. You can refer to the page Available Page Viewing Modes: Speed vs. Accuracy for details.