User Guide
Nitro PDF Pro MacOS

User Preferences

Open the Preferences by selecting Nitro from the menu bar, and choosing Preferences... from the drop-down menu (Command+comma).

General Preferences

Define 100% scale as:
Choose how to display your documents using either of the following options:

  • 1 point equals 1 screen pixel size
    Display a document at different dimensions depending on the screen's resolution.
  • Size on screen equals size on printout
    Display a document at the same dimensions regardless of the screen's resolution.

Initial window size:
Set the application to open a document sized to page height, screen height, or screen width.

Default zoom:
Set the application to open documents at 100%, 150%, Fit to Page, or Fit to Width. (Page Layouts and Views).

Initial sidebar mode:
Choose the initial display mode of the sidebar when opening a new document. (Sidebar).

Default view:
Choose Single Page or Facing Pages. (Page Layouts and Views).

Remember last page viewed for each document:Reopen a document to the same page where you left off. Checked by default.

Enable autosave and versions:Enable automatic file saves and support for versions. Checked by default.

Always show the File Open dialog on launch:Allow the "File Open" dialog window to appear every time the app is launched.

Lock PDF/A archive documents when open:
Make a PDF/A document uneditable when open.

Enable clicking on detected links:
Enable the automatic detection of context links such as emails and phone numbers.

Enable JavaScript:
Allow JavaScript to run in a document. Forms that perform calculations require JavaScript to function properly.

Restore display of all warning alerts:Allow dialogs displaying warning messages.

Editing Preferences

Default Font:
Choose the default text formatting (font and size) of a text field. This includes text fields from Markup Tools, like the Text Field and Comment tools. To change the default, click the Select… button, and choose a new font or size from the Font window.

Keyboard Increment:
Choose the keyboard increment, that is, the amount the arrow keys will move an object.

Gridline every:
Set the distance between gridlines. Go to the Arrange menu to turn on and off Show Grid and Snap to Grid. (Arranging Images and Objects).

Measurement units:
Select Keyboard Increment and Gridline units, either points, millimeters, or inches. (Measuring).

Show Guides:
Check if you would like to keep red alignment guidelines visible. (Arranging Images and Objects).

Automatically switch selection tools:
Check this option if you want the application to automatically switch between the Select Text and Edit tools based on the location of mouse clicks. For instance, if you click on an image, the application will automatically switch to the Edit tool so that you may move or resize the image. Conversely, if you click on the text, the application will automatically switch to the Select Text tool. If you have this feature unchecked, the currently selected tool will always remain active regardless of where you click on the page.

Keep tools selected after use:
Check this option to keep the Annotations, Drawing, and Form Element tools active for continuous use, rather than switching back to the Edit tool after each use. To quit the tool while in continuous use, click on another tool. If you have this feature unchecked, the tool will stay active for a single-use, then revert back to the Edit tool. To activate continuous use from single-use mode, double-click on the tool.

Lock images:
The application can automatically lock large images that it detects. This is useful when working with scanned documents. Default is set to Lock images '“Large enough to fill the page.”' Can be set to Always or Never.

Custom highlight colors:Create custom highlight colors that will appear in the Highlight button
highlight button

When checked, the characters placed in the Name: field appear as the name property of any new annotations added to the current document.

The name that will be used as the name property of new annotations. Defaults to the currently logged-in full user name.


Prompt for OCR when opening a scanned document:
Checked by default.

Perform OCR when selecting text on a scanned page:
Checked by default.

Rotate & deskew pages automatically when performing OCR:
Automatically detect and adjust rotated and crooked pages upon OCR.

Languages to recognize:
Check which languages you want to be recognized by OCR.

MRC compression level:
Select a compression level for scanned documents. File size and image quality have an inverse relationship where the best compression will result in smaller file size but reduced image quality. PDFpen provides four levels of MRC compression:

  • Best Compression
    Reduces file size with reduced image quality.
  • Better Compression
    Reduces file size with some reduction to image quality.
  • Balanced
    Reduces file size while maintaining image quality.
  • Better Quality
    Reduces file size without degrading image quality.
  • Best Quality
    Reduces file size while retaining the best possible image quality.

Select None if you do not want MRC compression applied during the OCR process.

OCR completed sound:
Select the sound to be played after a successful OCR.

OCR failed sound:
Select the sound to be played after a failed OCR.


Check for updates:
The application can check for updates when it is launched. Set how often you want to check for updates (hourly, daily, weekly, monthly). Uncheck for Never.

Include anonymous system profile information:
Allow information (macOS version, Mac model, CPU, etc.) to be sent anonymously during update checks.

Include beta builds:
Try the newest features, improvements, and enhancements. Use with caution.

Getting Started