Can I change the amount of "All capital losses used in 2024" manually?

It depends. You cannot opt out of taking capital losses to save them for next year. However, you will be limited to only $3,000, so any losses exceeding your gains plus $3,000 will be carried forward to next year.

However, if you had no income to absorb the losses, then you can carry them over. For example, if your taxable income was $1,000 before capital losses, and you had capital losses of $5,000, you can use $1,000 of losses and you would carry over $4,000 of losses to future years. TurboTax will compute this for you. 

Here is some information you may find helpful: Where do I enter a capital gain or loss?