Question

Where do i find previous versions of Studio one software (eg  version 6.6.1 ) on the Presonus site ????????????????????????????

Answer 1

https://my.presonus.com/products/all

Click that link, log in, and on the sidebar to the left select "Recording Software". This will show you all previous versions that you own. As fas as I know, Presonus doesn't sell older versions of Studio One directly, but people do sometimes sell their older copies on sites like eBay and Reverb.