Customise doesnt work at all, why?

I have switched on a child theme from the list and now want to change it, i have used the customise option, changed the colours, the screen clears and changes to the new colour. I click publish and it just goes back to before although it thinks the colour has changed in the options but nothing ever happens.

Also how do i completely get rid of the text in “home page” “customize” “main banner block” if i delete it all the default words come back so i have to leave a full stop on each line to stop it, the page builder refuses to work so stuck with this mess