You need to replace the partial_item_table.php of the application/modules/invoices/views and application/modules/quotes/views. As well as the style.css of the theme, you use.
The multi-row item tables were introduced due to users requests because single-line tables were just too dense and could not be viewed on regular monitors or laptop screens.
It’s up to the new maintainers to decide on whether to undo these changes, but instead of moving forth and back, implement a solution where the user can decide which version he want’s to use.
Point taken !
Still nowadays a minimun 1200 pixel wide on any decent screen to work !
The problem is changing the theme does not change the view. I will see what I can do to come over this.