InArcMapandArcGIS Pro, when you run aGeoprocessingtool the details of that run are stored in theGeoprocessing ResultsorHistory, and that prior run can then be reviewed and rerun in the future without having to set all of the parameters.
Example: ArcGIS Pro History.
InArcGIS Online Geoprocessing is called Analysis. However, there does not appear to be any Analysis History, yet, in ArcGIS Online. Then, you have to re-enter all of the parameters from scratch, every time you run the Analysis tool.