Charts different data source

Hi,

My problem. I have a workbook with more than 50 worksheets. All the
worksheet have the same structure and each I would like to embed 3
different chart, one for income, other for cost and another for Ebitda.
I would like to make a template for each chart and copy for the others
worksheet.

Questions:

1 - How can I make this dynamic as I would like to choose hom many
months I would like to show in each chart?

2 - How I keep the reference for the data source in each worksheet?

I tried to use the functions offset, 3d range and others functions but
I could´t make them work.

Can somebody help me.

Thanks in advance,

Andre