Soheil Bakhshi saves us some time:
I see some developers really hate the old style of the visuals when they have to work on an old report and it makes them crazy to see that the visuals style remains the same even if they create a new report page and add new visuals to the page. So some developers go through a lot of pain to get the visuals to work in the modern style. I even know some developers copied all queries from Power Query from the old report and pasted them to a new Power BI file. Then they used Tabular Editor to copy the tabular objects from the old report to the new one. And some even started to build everything from scratch. If you are one of those developers, be aware that there is a simple setting that can help to quickly switch all the old visuals to their new modern style.
Read on to learn which setting that is.