Set your BrainStorm defaults (auto-load, auto-save, Undo buffer, fonts, colours, print settings, paste settings, warnings).
You can also change the size of the 'Undo edit' buffer. This keeps details of up to 512,000 edit operations so that they can be undone and redone using the Undo and Redo commands. The default value is 1000. Merge, in this context, is regarded by BrainStorm as an edit operation.
Here are a couple of images from the Preferences dialogue:
The Smart paste settings are the system defaults for both Smart paste and Magic paste. They are applied to new models. Each can be overridden for the currently open model at the time of invoking the Paste operation.
Normal paste (Ctrl+V) can optionally use the Smart paste settings as well.
'Popup' is the most useful setting for 'warnings'. It explains what's happening and alerts you even if the sound on your machine is switched off.
See Magic paste for details of the Separator dialogue. This defines a sequence of characters and lines to precede each Magic paste operation.
Use: