Password protecting spreadsheets with macros
I have a spreadsheet in .xlsb format which is protected with 'password to open' to which I want to add a Excel 4.0 macro worksheet.
I know that I can save it as .xls and add the macro sheet, however, I am unsure if this will compromise the level of encryption provided.
Searching the internet I can't find a definitive answer as to whether the level of encryption is linked to the version of Excel used to save the file, or the document format used.
Please could someone advise me as to whether saving as a .xls will lead to the file becoming no longer secure.