Asslamo Allaikum,
The two foremost Salafi Scholars of our times say on the matter:
Shaikh Ibn Jibrīn (RA) wrote in his Sharh of the classic Hanbalī text :أخصر المختصرات
All of that which has been narrated is permissible, if someone folds them underneath the naval this is permissible, as it has been narrated from many of الفقهاء the Fuqahā’ yet what is preferred is to fold them above the naval or on the chest.
[Sharh Akhsar al-Mukhtasarāt page # 119]
Shaikh āli al-Fauzān ﴾ حفطه لله ﴿ warns in his book al-Mulakhkha al-Fiqhī:
We do not find any logical justification for strictness and narrow mindedness observed by some of youth nowadays when applying the acts of the Sunnah during prayer, which may lead them to perform it in a very strange manner. Some of them put their hands on the upper part of the chest, under the neck, instead of putting them on the chest or under the navel as stated in the Sunnah. [al-Mulakhkha al-Fiqhī Volume # 1 page # 127]
