Server icon, MOTD and basic settings

What this is about
When someone adds your server to their Minecraft multiplayer list, they see
three things: the name they typed, your server icon and your MOTD (the
short "message of the day" under the name). Both are set on the
Settings tab of your server, in the Minecraft Customization card at the
bottom of the page. The card shows a live preview of how the entry will look in
the game.
The card only appears on Minecraft Java Edition servers (Paper, Vanilla, Purpur
and the like). If your server runs another game, it isn't there. The other cards
on the Settings tab are explained in Server settings.
Changes apply after a server restart. Minecraft reads the icon and the MOTD when it starts. Save your changes, then Restart the server from the Console. Until then players keep seeing the old icon and message.
Server List Preview
The dark bar at the top of the card is drawn the same way the game draws the
multiplayer screen, with the real Minecraft font: icon on the left, name on the
first line, your MOTD on the two lines under it. It updates while you type, so
you can try things before you save.
Two things to know about the preview:
The name shown is your Server Name from the Rename Server card. In the game, players see whatever name they typed when they added your server. Only the icon and the MOTD come from your server.
Each MOTD line is cut off at the width of the entry, roughly 45 characters in the normal font. Keep your lines short.
Server Icon
The icon is a 64 by 64 pixel PNG file called 
server-icon.png in your server's
main folder. Minecraft ignores icons of any other size, so the panel crops and
scales whatever you give it to exactly 64 by 64 for you.
Click Upload (or click the square, or drag a picture onto it). Any common picture format works: PNG, JPG, GIF, WebP.
The Crop Server Icon window opens. Drag the picture to choose the part you want to keep and use the Zoom slider (1x to 8x) to zoom in. The Preview on the right shows the finished 64 by 64 icon at its real size.
Click Save. The icon is written to your server as 
server-icon.png and the preview updates.
Tips for a good icon:
Simple shapes and big details work best. At 64 by 64 pixels, fine text turns into mush.
Transparent PNGs stay transparent.
You already have a finished 64 by 64 PNG? Upload it as is; the crop window will show the whole picture selected and the panel keeps it pixel for pixel.
To go back to the default (the grey "unknown server" picture), click Remove
next to the Upload button and confirm. This deletes 
server-icon.png from
your server.
MOTD
The MOTD is the text under your server's name in the player's server list. It
can be up to two lines and uses Minecraft's colour and formatting codes. The
editor does the codes for you:
Type your text in the box. Press Enter once to start the second line (the editor won't let you add a third).
Select a word or a whole line and click a colour in the palette, or B, I, U, S for bold, italic, underline and strikethrough. The shuffle button is Minecraft's "obfuscated" style (constantly changing random characters).
The eraser button (Reset formatting) puts the selected text back to plain, and the star button (Insert symbol) drops in symbols such as ★ ❤ ⚔ ▶ that the Minecraft font can display.
Check the preview, then click Save. Discard throws away unsaved changes.
If you'd rather type the codes yourself, use 
& followed by the code, for
example 
&a for green or 
&l for bold. The editor turns them into the 
§
codes Minecraft expects as you type. Text without a colour code shows up grey
in the server list, like the game's default "A Minecraft Server".
Code
Colour
Code
Colour
&0
Black
&8
Dark Gray
&1
Dark Blue
&9
Blue
&2
Dark Green
&a
Green
&3
Dark Aqua
&b
Aqua
&4
Dark Red
&c
Red
&5
Dark Purple
&d
Light Purple
&6
Gold
&e
Yellow
&7
Gray
&f
White
Formatting: 
&l bold, 
&o italic, 
&n underline, 
&m strikethrough, 
&k obfuscated, 
&r reset everything.
A colour code also switches bold, italic and the other styles off. Put the colour first and the style after it (
&2&l, not 
&l&2). When you use the toolbar on selected text this is handled for you.
The MOTD is stored as the 
motd= line in 
server.properties. The panel keeps
the rest of that file exactly as it is, and writes special characters in a form
that every Minecraft server version reads correctly. On a brand new server
without a 
server.properties yet, the card tells you that saving will create
the file. The limit is 512 characters including the codes.
Other settings, such as max players, difficulty or PvP
This card only covers the icon and the MOTD. Everything else in
server.properties (
max-players, 
difficulty, 
gamemode, 
pvp,
online-mode, 
view-distance and so on) is edited by opening the file in the
file manager
on the Files tab. Those changes also need a restart. The Minecraft version
and the server type are set on the Startup tab,
not in 
server.properties.
Sharing the server with friends
Subusers
see this card when they have Files → read content. They need
Files → update to save a MOTD or upload an icon, and Files → delete to
remove the icon.