The first place to do this is during the customer creation on step 2

For an existing customer, go to the customer's profile->hit the Edit button for the service information->scroll down and select a preferred tech.

You can select multiple customers with upcoming jobs from the route > map page. Use the date range and technician drop down to display upcoming jobs in the map view.

Next, use the selection tools to select multiple locations. This is particularly effective when setting preferred technician by geographic area.

On the right hand side will be a list of all of the locations you have selected and an actions menu. Choose "tech" from that actions menu.

In the dialogue box that comes up, choose your preferred tech from the drop down and hit the assign button.

You will be able to see who the preferred tech is on the view/add page and be able to auto-assign the jobs based on preferred tech.

Another method is to reassign the previous tech's employee profile to the new technician. That way all of the information for the technician stays the same except their name and login credentials.

To do that, go to Employees > then select the technician profile that you want to reassign.

Next, select "Edit Details" for the employee profile.

Then, edit the details for the employee.

Lastly, reset the password.