There are different ways to highlight your pdf files, here we are going to start with Adobe Acrobat.
How to Highlight in Pdf with Adobe-Acrobat;
1- Click on “Edit” and “Preferences” key.
2- In “Categories” part click on “commenting”. In Making Comments part check Copy selected text into Highlight… box, after that click on Ok.
3- For have access to highlight key, you can click on View> Comment > Annotations, Or in the right side of your Adobe windows click on Comment tab and Annotations.
4- Click on Highlight key and after that, you can select the lines and words which you want to highlight.
How to Change the Color of Highlighted Part;
1- Right-click on the highlighted-part.
2- Click on Properties.
3- Click on Appearance and change the colour of highlighted-part.
4- You can change the opacity of the highlighted part and if you want to keep these modifications, for the next highlight part, Tick " Make a properties-default box" or Right-click on the highlighted text and click on “Make Current Properties Default”.
How to Delete Highlighted Part;
Right-click on highlighted Part and click on delete.
You can also click on File and Revert key.
How to Export Highlighted Text in a PDF;
1- Click on “Option” key and “Create Comment Summary”.
2- Create Comment only and Create Comment Summary.
3- You can see all the highlighted section, which were transferred to the new pdf file.
If you want to highlight the specific word in your pdf file you can go to How to Highlight Specific Words in a pdf page.