Is there a way to “tighten” the dashboard so it doesn’t rattle so much on bumps?

i have read a lot of 'eliminate the squeaky dash' threads (usually gen 3. but i have never read about tightening it down.
that being said, idk how it fastens in, so it is theoretically possible that there are screws of some sort.

 

That part of the car is poorly designed. I remembered when I drove a Prius for the first time the flimsy dash was the first thing I didn't like.

If yours is especially loose, probably best way to approach this is to find out if the speedometer (combination meter) has ever been repaired and if not making those repairs pre-emptively will allow you to remove that part of the dash to inspect all the fasteners and see if anything needs to be fixed.

As in Gen2 Prius has a known problem with the speedometer (combination meter) going blank when you start up the car because a capacitor goes bad. They had a recall for it long ago, but no longer. It's an easy fix if you have basic soldering skills.

There's lots of youtube videos you can watch to learn how to do this...

 

Lol, this comment!!!

 

In my 2007 various panels have rattled from time to time and each time I’ve found a clip that was not seated. Often once you locate the problematic clip, if it’s not broken or missing from a prior bad removal, a firm whack can fix it. Probably best to take a look at where the clips are on the dash panel from a YouTube video or tech drawing and see if that is the problem.

 

Gen2 is locking tabs . If you're sure everything is fixed and you're good up there you can apply goop strategically to some of these locking clips and they will stay locked they will release when you try to release them with a little bit of umph. But that goop works really well I guess you could use caulking too but caulking does not like to release goop is made to release when need to get up in there to do some work you might could do this on a gen 3 too thank God I haven't had to take my gen 3 dash pad apart because it looks like a noisy mess when you're finished just by looking at it I can tell this could turn into a real nightmare turn the stereo up good luck

 

It can be difficult to tell where a dash noise is coming from. The part which originates the noise can then transmit it along a surface so the sound seems to come from a different place. The OP might be able to better define the problem by driving on a known bad section of road and damping the dash by pressing on various points with one finger. Best done on an empty road since this sort of poking around can be very distracting. With luck pressing on one spot will reliably suppress the noise, which then suggests where to intervene to silence it once and for all.

I vaguely recall one of my cars from several decades ago which had a noisy dash that was "fixed" by wedging folded up paper between the A pillar and the dash. No idea what the actual problem was, but it didn't matter, the wedge immobilized the problem part of the surface well enough.