In the config.ini file, which can be edited on the Configuration page, you'll find sections labelled ui.overview.*. Entries under these sections can be toggled on and off (1 for on, 0 for off).
The Pioreactor has a permanent name (provided by the RaspberryPi), but you may want to relabel Pioreactors on the overview to make it easier to analyze and understand your experiments. You can choose to relabel all, none, or a subset of Pioreactors under the ui.rename section in the config.ini file, which can be edited on the Configuration page. The new labels will show up in the Experiment Overview and Pioreactors page. They will not be relabelled in the exported data, however.