Don't understand

My text color change in grey, yet I did not do anything for … I tried to get around by adding a class but it does not work on all texts …
In addition, I can not customize the display for Mobile and tablet through the icons in the top left, the changes are applied to all devices

so two major problems

your software is top but many malfunctions appear, some are minor others prevent me from advancing …

If you have solution it will be great thanks

Top left ?
You need to enter the tablet view, or mobile view on the top right, then you can customize each display, it should work