Select Tools > Options and click the Workspace icon.
This advanced setting is used by FME whenever arcs need be stroked into lines to make sure the distance between resulting line and the true mathematical arc is never more than the value specified.
You can set a default tolerance here for all workspaces, or you can set it on individual workspaces through Workspace Settings > Advanced > Stroking Tolerance.
Change the default setting for Geometry Handling.
Note that if you are editing a pre-existing workspace (a workspace that you have saved at least once) and you change the value for this setting in Workbench Options dialog, the new value will not immediately apply. To affect an existing workspace, you will have to manually change the value in the Advanced Settings of the Workbench Navigator pane.
If you are working in a new workspace that you have not yet saved, or if you start Workbench and edit this setting, your changes will be applied immediately.
This behavior prevents overwriting of any values that may have already been saved with a workspace.