A few tips.
Quoting previous posts has involved an extra step since a recent software change. You can either highlight part of the post and click the “Quote” button, or after seleclting “Reply” you can click on the “+” sign at the right of the menu and select “Quote whole post”. Note that when quoting the whole post, it will be automatically deleted by the software if it immediately follows the post you’re responding to.
For posting images, the imgur site is a good option (Google “Imgur uploads”). Remember to right-click and “display image in a new tab” and select that URL, ending in “.jpg”, and not the album image.
For posting YouTube videos, there is a bug in the software in our specific configuration, but a workaround is posted here. My own simple workaround is to just position the mouse cursor over “Reply”, paste the YouTube URL with Ctrl-V, and immediately click “Reply”. The trick is to do it quickly.