If you have an risk analysis with many items you can copy all content to a new analysis with a new name and also let the residual risk be the new start risk.

In the Risk Management index click on the copy icon to the right of the table on the Risk Analysis you want to copy

In the modal that pops up, give the new analysis a new name of your decision and tick of the box if you want the residual risk to be new start risk

Click on Copy and the risk analysis will be in the index with the new name you gave it

And also the risk items is copied