Under the "Project Accounting" tab, if the issue is related to a project or a project and WBS, you can select the project from the "Projects" window, link it with the document by sending and saving. Also, if you want to link the project's WBS, you can do the same.
If you want to associate more projects, you can select the first one, type the % rate and save. The system will show 2 more dashed areas to add WBS elements with more projects and show the remaining % rate to complete 100%.
To delete project records, you must check the "Delete" checkbox and click the "Delete" button.