My usual pipeline is to import freesurfer output into Brainstorm, import and coregister a CT scan that also has the ECoG strip, then use "SEEG/ECOG Implantation" to identify the ECoG strip. After the automatic detection of the strip, I manually go in and move the yellow dots onto the actual center of each electrode by dragging with my mouse. I do this because the coordinates of the electrodes matter to my project, and sometimes the yellow dots are considerably inaccurately placed. However, since updating brainstorm (not sure which update), I can no longer drag the yellow dots corresponding to the contacts, clicking just moves the crosshairs. Is there a modifier key that needs to be pressed in order to drag and move contacts with the mouse now?
You can still move the contacts from the MRI viewer, but you need to right-click on the channel file and select the menu MRI registration > Edit... MRI viewer: ...)`.
It is not possible to modify the position of the electrodes after opening the (same) figure with the menu Display sensors. The objective is to prevent the unexpected modification of contact positions when only exploring the volume for visualization.
What are you calling the "channel file"?
edit: think I found it. it's under implantation > "sEEG/ECOG"
If you are not familiar with what a "channel file" is in the Brainstorm database, I'd recommend you go through the introduction tutorials, at least until #19, and through the tutorial "EEG and Epilepsy":
https://neuroimage.usc.edu/brainstorm/Tutorials