I’ve heard you should do present tense for activities you are still participating in and past tense for activities you are no longer participating in but it sounds horrible when I do it in the present tense would it be acceptable to do it all in past tense?
An idea to consider: Sometimes, to save valuable space, you can leave out “I” and any ‘tense’. IMO the activities list does NOT need to be in full, grammatically-correct sentences. Think more resume-style, bullets.
For example: Involved in… Responsible for…
ex: NHS 3-yr member and Treasurer for 1 yr. Responsible for all fundraising deposits/petty cash disbursements.
With regard to your question though…if it sounds horrible to you, then you don’t want that on your app! you need to be happy with your final product. It’s fine to do it all past tense.