The item H box for "Other taxable private foundation," is located on Form 990-PF, page 1, item H Check type of organization:

The data entry for this check box may be found on the 990PF tab > screen 51 (Additional Info).

When this is marked on screen 51, the selections on screen 1 for item H are disregarded as only one type of organization selection is allowed. If the 990-PF is not an "other taxable private foundation," select the appropriate Tax-exempt status on screen 1: