The slash menu doesn't open.

It's on Mac only. It opens when / is the first thing on a line, and closes if you type a space after it. On iPhone and iPad, use the bar at the bottom of the Edit note sheet.

Write notes

Write and format notes in a markdown editor, and on Mac, highlight passages and comment on them.

Commands: /on Mac
On: Mac, iPhone, iPad

Write and format

Open a note and start typing. Edits are saved as you type.
Type / at the start of a line for the slash menu. Type to filter, then press ↩ to pick.
Select text for the formatting bar: bold, italic, highlight and more. Or right-click the selection and choose Formatting.
Markdown works as you type: # for a heading, - for a list, > for a quote, **bold** and *italic*.

Open a note. It shows as a page to read.
Tap the pencil (Edit note), or Edit in the details panel.
Write in the Edit note sheet. The bar at the bottom has headings, bold, italic, lists, quotes and more.
Tap the check (Save note) to save. Closing the sheet discards your changes.

On Mac, click the markdown button at the bottom right of a note (Markdown shortcuts) for every key, such as ⌘B for bold and ⌘I for italic.

Highlight and comment

On Mac, a highlight made from the formatting bar shows under Comments in Info, so you can find it later. For PDFs, see PDFs and highlights.

Select a passage.
Click the highlight button in the formatting bar to mark it.
Or click the comment button. Info opens with the quote. Type your comment and send it.

Not available on iPhone and iPad.

Typing ==text== makes a plain mark that doesn't show in Info. Use the formatting bar for a highlight that does.

Where notes are read only

On Mac, a peek and the Inbox's side view show a note as a page to read. Open the capture to edit it. A voice note's Notes tab is read only too.

Questions

Do I need to save?

Not on Mac: edits are saved as you type. On iPhone and iPad, tap the check in the Edit note sheet.