Hello and welcome to Apple Support Communities, matyasir.
If I understand your post correctly, you're unable to save comments to PDF files in Preview. I'd like to help.
Safe mode will tell us if the issue is related to a startup item or plugins, and sometimes corrects the issue. This article will tell you how: Use safe mode to isolate issues with your Mac
If everything is working correctly in safe mode, but is not working when you get back to your user account, please check the section titled 'If an issue doesn't happen in safe mode' for the next troubleshooting steps.
If the issue continues while in safe mode, a test user will let us know if the issue is isolated to your account, or system wide: How to test an issue in another user account on your Mac. If the issue happens in the test user also, then please check the section titled 'If an issue happens in more than one user account.'
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Let us know if that resolves this issue for you.
Thanks for using the Apple Support Communities. Take care.

1. Annotation Apps For Windows 10

Annotate an image in Preview on Mac. You can use the editing tools in the Markup toolbar to mark up an image file, providing feedback or pointing out something you want to remember. If the image is on a page in a PDF file and you want to comment on only the image, you. Oct 20, 2019  The editing features give you all you expect from a native Mac OS X application. Export to layout applications or to time-code savvy applications like Annotation Edit or Final Cut Pro, print or email files as PDF. Files may be sent to and edited by other applications, without loosing active time-code markers to directly jump to selected scenes.

Preview User Guide

You can use the editing tools in the Markup toolbar to mark up an image file, providing feedback or pointing out something you want to remember.

If the image is on a page in a PDF file and you want to comment on only the image, you can extract the image as a separate image file. See Extract a PDF page as an image for instructions.

If you only want to comment on part of an image that you’ve opened in Preview, you can select part of it, choose Edit > Copy to copy just that part, then choose File > New from Clipboard to create a new file. You can also crop the image to remove areas that you don’t want.

Note: If you annotate an image file, you can’t edit, move, or delete the annotations after you save the image. If you think you’ll need to change annotations later, you can convert the image file to a PDF file, then add annotations to the PDF.

Annotation Apps For Windows 10

1. In the Preview app on your Mac, if the Markup toolbar isn’t showing, click the Show Markup Toolbar button .

2. Use the tools in the toolbar to mark up the image (or use the Touch Bar).

   Tool				Description
   Rectangular Selection				Use any of the following shape tools to select an area in an image and then crop, copy, or delete: Rectangular Selection Elliptical Selection Lasso Selection Smart Lasso See Extract an image or remove a background.
   Instant Alpha				Remove the background from an image.
   Sketch				Sketch a shape using a single stroke. If your drawing is recognized as a standard shape, it’s replaced by that shape; to use your drawing instead, choose it from the palette that’s shown.
   Draw				Draw a shape using a single stroke. Press your finger more firmly on the trackpad to draw with a heavier, darker line. Note: Unlike the Sketch tool, the Draw tool doesn’t recognize standard shapes. This tool appears only on computers with a Force Touch trackpad.
   Shapes				Click a shape, then drag it where you want. To resize the shape, use the blue handles. If it has green handles, use them to alter the shape. You can zoom and highlight shapes using these tools: Loupe : Drag the loupe to the area you want to magnify. To increase or decrease the magnification, drag the green handle; drag the blue handle to change the loupe size. Highlight : Drag the highlight where you want. To resize it, use the blue handles. See Rotate and modify shapes added to a PDF for more options.
   Text				Type your text, then drag the text box where you want.
   Sign				If signatures are listed, click one, then drag it where you want. To resize it, use the blue handles. To create a new signature: Using your trackpad: Click Trackpad, click the text as prompted, sign your name on the trackpad using your finger, then click Done. If you don’t like the results, click Clear, then try again. If your trackpad supports it, press your finger more firmly on the trackpad to sign with a heavier, darker line. Using your computer’s built-in camera: Click Camera. Hold your signature (on white paper) facing the camera so that your signature is level with the blue line in the window. When your signature appears in the window, click Done. If you don’t like the results, click Clear, then try again. Using your iOS or iPadOS device: Click iPhone or iPad. On your iPhone or iPad, sign your name using your finger or Apple Pencil. When your signature appears in the window, click Done. If you don’t like the results, click Clear, then try again. Your devices must meet Continuity system requirements. See the Apple Support article System requirements for Continuity on Mac, iPhone, iPad, iPod touch, and Apple Watch. See Fill out a PDF form.
   Adjust color				Change values for an image’s exposure, contrast, saturation, tint, and more. To have the values automatically adjusted, click Auto Levels. To return to the original values, click Reset All.
   Adjust size				Change an image’s size and resolution.
   Shape Style				Change the thickness and type of lines used in a shape, and add a shadow.
   Border Color				Change the color of the lines used in a shape.
   Screen sharing app mac os x. Fill Color				Change the color that’s used inside a shape.
   Text Style				Change the font or the font style and color.
   Annotate				Annotate the item by sketching or drawing on it using your nearby iPhone or iPad. The Annotate tool appears blue when your device is connected; to disconnect your device, click the tool again. Your devices must meet Continuity system requirements. See the Apple Support article System requirements for Continuity on Mac, iPhone, iPad, iPod touch, and Apple Watch.