how do i increase font size on the headings-Tax invoice, Delivery notes etc
You cannot. That was just changed across all forms. The one place you can modify this is on the sales invoice, using a custom view template. But that requires recoding the entire invoice template in HTML.
The headings on all reports have been always 24px. The headings on other documents (e.g. invoices, quotes etc) have been decreased from 32px to 24px to make it consistent with reports.
Why do you need larger font-size for headings? New font size is still larger than anything else on the document. It’s just that 32px felt too much especially on documents with longer titles such as
Purchase Order where the title would take half of the printed page. And that still doesn’t account for variations in other languages where the title was even longer.
just though that maybe some features were fading.