Dynamics 365 for phones and dynamics 365 for tablets use forms as Web apps. How the form is displayed in the application is optimized for the mobile experience. Shows reflow from Web applications to tablets and mobile apps:
WEB Application
Tablet PC app
Mobile app
Dynamics 365 for phones and tablets does not provide the form switching feature. If the entity has more than one main form, the main pane that is displayed depends on the order of the forms you set and the security roles assigned to the form. More information:
When you customize a form, you can hide the following items from the Dynamics 365 experience for your phone:
Field
Part
Entire tab
Using this approach, if you think that mobile users only need to focus on the primary contact information, for example, you can hide the contact details from the phone app when customizing the form.
Show hidden details from Dynamics 365 for mobile
When you customize a form in the Form editor, select the field, section, or tab that you want to hide.
Click Change Properties.
Clear the available on phone, and then click OK.
Reference Address: http://www.cnblogs.com/Earson/p/dynamicsmobileform.html
Customize Dynamics for phones and tablets 365 (ii): Form customizations