Select Tools > FME Options > Workspace Defaults.
Arc/Ellipse Stroking
This advanced setting is used by FME whenever arcs need be stroked into lines to make sure the distance between the resulting line and the true mathematical arc is never more than the value specified. For more information about how arc stroking works, see Stroking Tolerance.
When you update this setting, it affects stroking tolerance for all new workspaces. To update stroking tolerance on previous workspaces, or to apply a different setting on individual workspaces, see Stroking Tolerance.