The red markings indicate a blocked peripheral device that is already in use in that particular setting.
As the name Discovery Board suggests, these boards are designed to help you discover the capabilities of the target microcontroller. In order to help you as much as possible, external devices are already connected so that you can start programming immediately.
In order to explore the full range of possibilities of the MCU or to program completely free, either your own separate board is necessary or one of the NUCLEO boards, e.g. the NUCLEO-F767ZI if it fits your needs (the STM32F769 provides a MIPI-DSI Interface, while STM32F767 a parallel LCD-TFT interface).
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/Peter
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