Here is an example of an AFL (AmiBroker Formula Language) code snippet that could help you spot when the current volume is three times larger than the last volume:
// Get the volume data
volumeData = V;
// Calculate the condition where the current volume is 3 times larger than the previous volume
largeVolume = Ref(volumeData, -1) * 3 < volumeData;
// Plot the condition on the chart
PlotShapes(IIf(largeVolume, shapeStar, shapeNone), colorYellow);
This code will plot a yellow star on the chart whenever the current volume is three times larger than the previous volume.