Managing large charts

Hi all, I wanted to ask if anyone has any advice on managing large Visio diagrams?

My problem is that after surveying the team, writing my notes, heading into Visio and drawing out a long detailed flow across 7 swimlanes - is that it doesn't print well at all! And users are struggling to work with it as they have poor eyesight.
I have built my chart as Landscape left to right, with AutoSize = ON. Then, once the diagram was finished I changed the Paper Size to A3, and set the Print settings to A3. However when printed, due to the long shape of the chart, the diagram is only printed on the lower half of the A3 sheet and all text is really small.
Is there something I should have done first or is there something I can do to this to fix this chart up? I'd ideally like to avoid splitting this flow into many small ones - it is useful to view in one sitting - and I'd be very happy to split it evenly across many A3 sheets - so long as users can read it.
Apologies to post for help I just can't see much online about managing large diagrams? Appreciate any assistance anyone can provide.

Cheers