Failure to display continuously read information from the mega serial port of mo

I am trying to receive data from a device through the mega serial port. This data is sent continuously from the device and is read by the mega serial port. But when I want to see them in the monitor serial, only 64 bytes of data This is exactly equal to the data buffer capacity of the serial port, and after 64 bytes the last received data is repeated and the new data is not displayed. The question is whether the monitor series can only display 64 bytes and how can I see the next data read by Mega?
And is the information entered in the mega available in the serial buffer port, regardless of whether it is not shown in the monitor series?
Thanks for your guidance

Of course the monitor can display more than 64 characters. What use would it be if it did not? Please post your entire sketch.