Running Total Formula Multiple Columns

Try this:

let

//change next line to reflect your actual data source
    Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
    #"Changed Type" = Table.TransformColumnTypes(Source,{
            {"End of week", type date}, {"New Prospects", Int64.Type}, {"Closed Prospects", Int64.Type}, {"Current Prospects.1", Int64.Type}}),

//Running Total List
    #"Current Prospects" = List.Generate(
        ()=>[rt=#"Changed Type"[Current Prospects.1]{0}, idx=0],
        each [idx] < Table.RowCount(#"Changed Type"),
        each [rt = [rt] + #"Changed Type"[New Prospects]{[idx]+1}- #"Changed Type"[Closed Prospects]{[idx]+1}, idx = [idx]+1],
        each [rt]),

//Replace Current Prospects column
    #"Running Total" = Table.FromColumns(
        Table.ToColumns(Table.RemoveColumns(#"Changed Type",{"Current Prospects.1"}))
         & {#"Current Prospects"},
         type table[End of Week=date, New Prospects = Int64.Type, Closed Prospects = Int64.Type, Current Prospects.1=Int64.Type])
in
    #"Running Total"