I am not literate in right program to do this. THX hickori
Please tell us the last 3 or 4 letters of your document’s file name, that is, the letters after the period (point). Are they .pdf or .jpg or .odt or .docx or something else?
You could use Draw.
If the scanned image is in an image format such as jpg, png or gif, you can insert it into Draw (Insert > Image… and navigate to file, select and OK).
The default layer is Layout so we need to lock that layer to prevent accidental selection of the image of the form. Right-click on the Layout tab at the bottom of the page and select Modify Layer, in the dialog that opens click Locked.
You now need to create a new layer to work in. Right click on a tab and select Insert layer, name it or leave it as the default numbered layer.
The new layer is still selected so draw text boxes over the fields and fill them in. File > Export > Export as PDF
You can do the same thing with a pdf if it is just a jpg in a pdf wrapper.
You might find that some pdf readers might be able to identify fields and allow you to fill them in.