The actual Line 323 on the Schedule 1 is based on a calculation of other amounts (found on the S11). Where you enter the tuition amounts depends on whether or not you claimed any tuition on your return.
1. If you claimed an amount for tuition on line 323 and you want to adjust that amount (add carried forward amounts), the spot to enter the information is present without selecting a line number. The current amount you've claimed is also present. See picture below.
2. If you didn't claim any tuition amounts, select line 320 from the list. See picture below.
* Line 320 is from the Schedule 11. It's the total of the eligible tuition paid in the year plus the unused tuition amount you had from previous years