Some will not stay on the shoulder, and really it's a very unwise thing to encourage anyway UNLESS you are
>> sitting on a nice soft bed
>> sitting on a nice soft lounge
>> sitting on a carpeted floor
>> sitting on the grass.
they are prone to leaping off when young , and can easily loose their grip and slip or roll off when larger and do very serious injuries to themselves when they hit the hard ground or a hard unforgiving floor.
Best to encourage safe spots to sit on you ie
>> the lap
>> along your forearm
>> in the crook of the elbow
>> on the tummy
>> on your chest
where you can give good support and prevent them from falling / leaping off.
As to getting him comfortable and relaxed with being handled by you , let Titus take the lead , he'll let you know when he's ready for more handling , so patience and small steps are the way the way to go.
Giving food treats each time as the start helps , they learn the handling is associated with something pleasureable to them , and it's a good way to build trust.