Get data from CSV file reads numeric columns as text

Hmm, interesting. I was not able to reproduce with a file like:

ID,Val1,Val2,Val3,Val4
1,1000000,1000000,1000000,1000000
2,6000000,1000000,1000000,1000000
3,600000000,1000000,1000000,1000000
4,1000000,1000000,1000000,1000000

You can select multiple columns and then Change Type. You can also use Advanced Editor, line highlighted below.

let
    Source = Csv.Document(File.Contents("C:\temp\powerbi\largeNumbers.csv"),[Delimiter=",", Columns=5, Encoding=1252, QuoteStyle=QuoteStyle.None]),
    #"Promoted Headers" = Table.PromoteHeaders(Source, [PromoteAllScalars=true]),
    #"Changed Type" = Table.TransformColumnTypes(#"Promoted Headers",{{"ID", Int64.Type}, {"Val1", Int64.Type}, {"Val2", Int64.Type}, {"Val3", Int64.Type}, {"Val4", Int64.Type}})
in
    #"Changed Type"

If the column names are consistent or in the same position (do it before promoting headers) then you could just copy and insert the line of code as appropriate. What version are you on? I seem to remember this sort of thing happening to me in the past but I can't reproduce on the current version.