I use the template IMO for my domain wijhelpen.eu
Within the adminsettings of the template i followed the advices from the template documentation:
> development
> compile less
> compression
> bootstrap

after i did this and saved it there are only a few errors when i check it at the w3c (i do know that these are not really errors)
But my question is if i want to change things over in the website lets say for colorsettings or so. Do i have to undo the settings? Can you give me advice what i have to do before i change some settings

Hi there,
the W3C validation errors are not important:
yoast.com/w3c-validation-seo/

If youre site is still in development use these settings:
> compile less = yes ( only if you edit some less files, otherwise you dont need)
> compression = no
> bootstrap = yes

If your site is ready for take on:
> compile less = no
> compression = yes
> bootstrap = yes

Thank you for the answer (i was a few days in Cochem, so not able tot answer)
But what do i have to do if i want to change something AFTER:
If your site is ready for take on:
> compile less = no
> compression = yes
> bootstrap = yes

If you want to edit site after publishing you have to disable the caching/compression and delete the Browser cache.
And if you change something in Customizer the theme will compile less automatically.