Hi, I've tried for hours to figure out how to create a custom drop-down menu (say, field named "X" with options "Y", "Z", and "A"), but I could not find documentations and/or means of doing this. Does anyone know how to solve this problem? Thanks in advance.
No you can't change the size of the fields available.
If you have data in a 255 text field and you wanted to increase the field to 4k text field you cant. You can set up a 4k field and transfer the data from the 255 text field into the 4k field using data exchange or UI rules and a code field.