Getting a new PC, is anything important *not* saved server side?

[Omedon]

I’m pretty sure I know the answer to this, but I’m a little confused by one of the options seen before logging in, so let me ask just to be sure.

I intend to get a new PC soon, and one of the first things I’ll be installing will be FFXIV of course. On a fresh machine that’s never seen this game before, how much of what I enjoy in the way of settings and especially macros might I need to back up locally on my end in order for a seamless transition to the new computer? I was pretty sure the answer was “nothing, it’s all saved server side” until I saw a button to push my settings to the server. If the game doesn’t save my settings and macros server side by default, why does that button exist, and if it doesn’t, how were my ARR era character’s macros still intact when I returned in Shadowbringers? Has something changed recently?

I don’t use anything 3rd party, so that’s not a concern. I’m just worried about my macros and settings here!

Thanks in advance for any and all helpful replies!