Edge 1030 GPX file not aligned, best way to correctly it?

inkj

I imported a few rides as an GPX file, into Garmin Connect for my Edge 1030, I found most of the route is slightly off.

Which makes cycling journeys for the first time a lot more confusing. As I'm hardly ever actually shown as on the road/path correctly. It's a mess of seeing the real road and the line I'm being told to ride on - often not a road or pathway at all.

How can I correct the route [ideally in Garmin Connect before I send it to the device] - so the route is actually on the roads/paths/etc and not slightly off?

Do I have to go through the whole map manually - or can I click an option to make it all snap to the nearest real road/path?

My worry with the snap option - is that Garmin will recalculate the ride and change sections. Too often Garmin sends me to impossible footpaths that clearly no bike can fit on. Ok it's happen on two rides - but that is too often for me.

Thanks for any help