In the Menu Bar, click Edit > Preferences, then on the left side of the dialog box, select General Settings > Copy and Paste. After making any changes, press Apply and Save to save them.
Paste Touch Sensors - Pastes all touch sensors from the copied nodes and their subtrees. Before doing this, check whether you want this before continuing.
Paste Animation Curves - Pastes all animation curves from the copied nodes and their subtrees. Before doing this, check whether you want this before continuing.
Merge Materials - Merges all materials with the scene's material pool. Before doing this, check whether materials from the copied nodes and their corresponding subtrees should be merged with the scene's material pool or not. All materials are compared with the pool materials. If all properties of a material are equal with one in the pool, including its environment, it is not added as an additional material. Instead the material from the pool is used. If a material has no counterpart in the pool, it is added. If this is unchecked, all materials are added to the pool, which may result in copies of materials.
Environments - Sets what happens to imported environments. Choose one of the following:
Merge with Scene - Merges the environments with the environments in the scene, using the same strategy as merge materials.
If this option is selected, the material comparison assumes the default environment as the environment set for the copied materials.
Show Dialog - When checked, the dialog will not appear again and the copy paste will apply the last given settings.