Select the Yellow GRBL button, then select Spindle for the mode. If your grbl settings do not appear in the left edit window, select the GRBL Settings button. Verify your grbl settings are correct for Spindle use and if they are not, edit them. Then select the Save button and save your settings to the spindle.txt file. Select the Laser mode and edit the settings for Laser use, then select Save. Save those settings to the laser.txt file. Select Send so PicSender changes the grbl settings to the S3 board. Now select the Use Auto Settings, so when changing between the Spindle & Laser modes, PicSender will load/change the grbl settings automatically and it will no longer come up with that irritating message every time you connect to the Com port.