Welcome to the world of conditional compile.
Here are the lines in the ubitx.h file that you need for the stock standard V5 board (you can copy/paste to replace existing lines 25 to 35 with the text below):
//Ubitx Board Version
#define UBITX_BOARD_VERSION 5 //v1 ~ v4 : 4, v5: 5
//Depending on the type of LCD mounted on the uBITX, uncomment one of the options below.
//You must select only one.
#define UBITX_DISPLAY_LCD1602P //LCD mounted on unmodified uBITX (Parallel)
//#define UBITX_DISPLAY_LCD1602I //I2C type 16 x 02 LCD
//#define UBITX_DISPLAY_LCD1602I_DUAL //I2C type 16 x02 LCD Dual
//#define UBITX_DISPLAY_LCD2004P //24 x 04 LCD (Parallel)
//#define UBITX_DISPLAY_LCD2004I //I2C type 24 x 04 LCD
//#define UBITX_DISPLAY_NEXTION //NEXTION LCD
This generates a program that just fits in the Nano's memory but you have all the features enabled.
Later if you want to, you can remove the features you do not use to make your menu simpler.
This is done in lines 62 to 83. To disable a feature change the "1" into a "0" (zero, not "O").
Example to disable WSPR:
Change line 73 form:
#define FN_WSPR 1 //1044
#define FN_WSPR 0 //1044
The number after the // is an information Dr Lee has provided to indicate how much memory you save/use by disabling/enabling that feature. This is useful if you want to program other functions and need to make some room by removing unused features.
Hope that helps,
73, John (VK2ETA)