The Next Touch Functionality of Projects is designed to give salespeople a pre-sales set of tasks with dates to complete them to push the project along the process without missing anything.
When you set the Next Touch Type and Date on a project for the first time, it will appear on the salesperson's events calendar. Once there, salespeople can drag and drop to change the Next Touch Date and can right click to change the Next Touch Type.
You can set the Next Touch Type and Date from within the Project Information window, by right clicking on one or more projects from any grid or tree where you see projects (and can access them), or by right clicking on a pre-set Next Touch item in the Events Calendar.
Changing Next touch in Project Information Window.
Right Clicking on multiple projects to set Next Touch (be sure to click the "Set" button after making a selection).
Update Touch Type & Date directly from Current Opportunities
See here for additional details on Touch Types and Touch Dates in regards to Leads.