In only one of the migrated projects in Application Lifecycle Management (ALM) 11.52 the user does not have rights to make changes. Everything is shown greyed.
In the other projects user can change everything. User is member of TD Admin group and the project isn´t linked to a template.
Most probably the project was linked to a template when exported before the upgrade. Thus the user permissions remained locked.
Adding the project to a template and removing it again has fixed the problem.