Last time we used operand types to make a function more readable and understand its behavior better. Converting operands one by one is fine if you need to do it a few times, but can quickly get tedious if you need to do it for a long piece of code.
To convert operands of several instruction at once, select them before triggering the operation (either using the corresponding hotkey (e.g. R), or from the Edit > Operand type menu.
If you have a selection when triggering one of these actions, it won’t be performed immediately but another dialog will pop up first:
Here, you can tell IDA which operands you want to actually convert. The following options are available:
P.S. you can use this feature not only with instructions but also data. For example, for converting several separate integers in the data section to decimal or octal. In such case, the ‘operands’ will be the data items.
See also: IDA Help: Perform en masse operation