In an image forming apparatus where an amount to be printed due to execution of a job designating printing according to a first printing mode exceeds a first printable amount, a screen is displayed to accept an instruction for changing printing according to the first printing mode designated by the job to printing according to a second printing mode. When the instruction is accepted on the screen, a print setting screen which is able to accept a change of print setting of the job is displayed. If an amount printed according to the second printing mode would exceed the second printable amount even if print setting of the job is changed, the print setting screen is repeatedly displayed until print setting of the job is set such that the amount to be printed on printing according to the second printing mode does not exceed the second printable amount.