With the iPad connect to your computer and while iTunes is running - you can right click on the iPad name on the left and select - Reset All Warnings.
You can do this in iTunes as well.
Are you using the same Apple ID on all devices and in iTunes?
What do you mean by update all apps? So you mean sync all apps? If that is what you mean, you have to select the apps to sync in iTunes when the the iPad is connected to the PC and with iTunes running.
Click on the iPad name on the left side under devices, click on the apps pane in the iTunes window on the right, click on the sync apps heading, click on all of the apps that you want to sync and then you click on apply in the lower right corner.
Is that what you are trying to do?