Use the File Browser to Choose the Diff Operation

Unlike other views in which AccuRev selects the type of diff operation to perform when submitting elements to code review, when you submit an element to code review from the File Browser you can choose whether you want to diff against backed, basis, or just your changes as described here:

Backed Version
Compares your file with the version currently in the backing stream. For example, you might use this choice to see all the changes you have made to this file since you updated your workspace and starting working on the file. (And assuming no one else has promoted a new version to the backing stream in the meantime.) This might include the changes stored in several intermediate versions that you have created with keep.
Basis Version
Compares your file with the version that you started working with, before making your recent changes.
My Changes
Compares the workspace version with the common ancestor in the backing stream. This option is useful for files that have an (overlap) status because it identifies the changes in the workspace that did not come from the backing stream. The My Changes option is the equivalent of diffing against the last version that you merged with.