How to change the colour of the navigation line?

I’ve also struggled with this. Couldn’t work out which road I was supposed to be taking on a recent run!

You didn't find a solution yet I suppose? 

Try this.

Settings>Map>Track Color

Unfortenately that changes nothing. When I look that up track colour is the piece of the track that you already walked so behind you and not ahead of you

unfortunately there is no way that I know of to change that.
Maybe if you change the map theme or try a different one with more contrast, the GPS track will be more visible ?

i have the same issue with the 5x. for me what helped is to set the map to less detail and this way the magenta line is easier to see. garmin needs to make the line thicker

It has recently been a small change of the navigation line in my 6x. The edges of the  magenta line have changed from black to white. See example in my thread. forums.garmin.com/.../new-format-on-follow-course--line

This small change did that I have much harder to to see it.

Im still on v3.0 and the only upgrades I have done is maps, sns and the ant/ble beta.

Do you still have black edges?

Not sure what you mean by black edges.. 

Borders on both sides on magenta line.

Before

Now

The look is thinner without the black borders or edges. I don't know another English word for it.

Got it. But no edges. Really an unclear line. But.. I got a workaround, well I didn't invent it but someone in the comments down below suggested to change the contrast and that worked. The line is clearer (the map is uglier) so untill Garmin lets me choose my own colour its solved for now