With PB and PD you may notice that within the 'Current Selection' box, the selections will have a blue or green next to them. A blue box means the filter is locked, so if you click clear or add more filters this selection will not change. This is very useful when you want to do analysis for your trust over a certain date range, for example. You can lock some of the selections in place so that you do not lose them.
There are multiple ways to lock/unlock a selection. If you wish to lock all the current selections you can do so by clicking the padlock at the top and all of the selections will lock in place, evident by the blue box next to the selection. Similarly, you can unlock all selections using the open lock button.
If you wish to just lock or unlock one particular selection you can right-click on the selection and select 'Unlock' or 'Lock'. There is also the option to use this method to lock and unlock all selections.